Author's Notes:

Contains: incest, intimately trapped, unavoidable cumming inside during estrus, impregnation risk, impregnation play, modest cum inflation

Ok, this chapter is downright gratuitous. The story description says in the Story Contains paragraph "Sex. Lots of sex." and here's a good chunk of it. Next chapter still has sex, though the drama tag will really start to kick in, but only after this pile of excess.

Have to wonder what readers are thinking will happen after this...

An indeterminable amount of period of time passed before Twilight finally managed a vaguely coherent, rather delirious whisper, her mind still floating as a forehoof rubbed around the side of her stomach, absently wondering if she could detect the results of her tight-feeling womb on the outside. “Oh Shiny, you left me feeling so full… You feel so good inside me… Every time more of your semen was sent into my uterus, it burned so hot I thought I was going to melt! It all still feels so warm…”

Her brother nuzzled her in a daze, his mostly hard cock already had signs of fresh life as he began to firm back up inside her marehood. Making a slow attempt, Shining discovered he couldn’t pull away, despite feeling the limp hold of her hind legs around him that somehow managed not to fall away. Lacking a choice in his current exhaustion, he settled back down against her, what little part of him that he’d slipped from her just sank back inside her as she cooed and squeezed down on him again. He spoke in a soft, weary tone, his nose rubbing just below her ear. “We’ve really messed things up, Twily. Why can’t I pull away so I can, uh, remove myself from you?”

With her mind starting to clear, Twilight tenderly rubbed her forehooves over her brother’s ribs as she tried to stop her body from clenching around his shaft. Sniffling as tears slowly began to slip from her eyes, she tried to keep herself calm and her voice steady. “I know… M-me fizzling our magic that hard probably rattled the spells. Nothing dangerous or bad should have happened, but from what seems most likely with the signs I’m starting to notice already, they appear to stay triggered for now, stuck on active… And I-I can’t do anything to fix or undo them until m-my magic is working again.”

Seeing his sister start to cry, Shining found himself refocusing faster and licked her cheek with gentle compassion, then kissing her temple. He tried not to think about how he was restored to full strength inside her without his even trying, or the tingle he felt each time her tunnel shifted around him, let alone the occasional clenching pull of her body wanting even more of his essence. “Hey now, we’ll get through this, ok? I’m not going to turn you away or something because of this. Neither of us knew. It’s hard now, but we just need time to figure this out.”

Twilight nuzzled her brother, feeling his cock beginning to twitch with a fully restored arousal already. She began to suspect the stamina spell she’d used was stuck in a constant active state, too. If that was the case, then for possibly over an hour, unable to tell how long the two of them had been trapped in that overwhelmed euphoria they’d shared, she couldn’t use her magic and undo the spells keeping them so intimately pressed together. In that time, he would have only a couple seconds of refractory period, then immediately start to build up again. She also knew that the way it worked, he’d either get increasingly aroused, or far more likely, wind up climaxing inside of her again just from her own rhythmic squeezing because of her estrus.

A quick factoring of variables, she realized Shining would probably cycle through recovery and release at least four to eight more times within the first hour they were going to be stuck together, assuming the stamina spell wasn’t also altered on the strength of the effect. Even at the level she’d cast it, her womb really would be quite swollen with a stallion’s seed, her own brother’s seed, by the time she could fix the spells and they were able to separate. Just the single load of semen he already gave her had left her uterus feeling tight. A perverse part of her mind knew she was more than a little intrigued at what she’d feel with far more inside her.

After she had some time to go over everything in her mind, occasionally pausing as her clenching nethers around his shaft made her quiver, she knew the only thing they could do was wait out the fizzle. At several points, it was a conscious effort on her part not to start rolling her hips as her estrus gradually made her more aroused. A ready stallion was already inside her, her estrus indifferent to who it was, and keeping her mind clear was a challenge. Twilight swallowed back an urge to whimper, though from stress or raw arousal, she couldn’t even tell. Realizing the inevitability they were faced with, and the very short list of choices left to her, there was only one viable course of action left in her mind.

Twilight knew it made no practical difference to their situation now, and at least they could have this one experience. She stopped trying restrain her marehood as her tunnel tugged eagerly at his rigid, twitching shaft. Her hormone-laden body certainly had no hesitations over seeking more of his seed, indifferent to the source. A faint pleasured moan slipped out as she focused on the heat of him laying so deep within her body, how good it felt to be almost surrounded even as he left her feeling full with his buried length.

She turned her eyes to him, but he’d have to lift his head for her to look into his face, rubbing her cheek against his head and neck. “Shining, just make love to me for now. We’ll have to worry about what to do later.”

His head lifted up so he could stare at her in disbelief. “Twily, haven’t we done enough?”

She sniffled again and gave him a tremulous smile. “It’s the stamina spell I gave you. If my calculations are right, I don’t think it shut down after restoring your erection. I’m pretty sure it’s stuck on active, too. That means it won’t matter how good you are at holding yourself back while you’re inside me. I can’t stop my estrus from trying to stimulate you, and the spell will keep making your arousal stronger until you can’t resist anymore and the smallest brush will make you release. It could be an hour or longer before the fizzle ends. By the time just that first hour is up, you will be putting even more of your semen inside me.” Twilight paused and took a shaky breath, feeling more turned on by the second. “At least four more times, maybe even eight times, assuming it takes around a full hour and my math is right. You will be ejactulating inside me with enhanced semen volume several more times before we’re done. If it’s running stronger than I set it, who knows how much of your love I’ll have sealed away inside me when we’re done…”

Shining winced, then began to look much more worried. “Wait, if those spells were messed up… Twilight, what about the contraceptive spells?”

A soft, resigned laugh escaped her mouth. Twilight let out a gasp as she gave in the rest of the way, openly squeezing her marehood around his shaft with full intent and desire. She let herself enjoy how her estrus was being agitated by having such a ready stallion buried inside of her, her body knowing more seed would fill her soon, and it was making her own arousal continue to rise. “Shiny, the damage is already done either way. While the separate magical resonance of another pony’s spells is less likely to be affected by a fizzle like that, it doesn’t change the fact we can’t separate or use any magic right now. And my uterus is already filled with your semen as it is, or with you being unable to avoid adding more. You won’t be making anything any worse by making love to me until the fizzle ends and I don’t want to spend all that time panicking when it won’t matter either way. I’ll check the spells when my magic works again. For now at least… C-can you…”

Twilight swallowed the lump in her throat, a vulnerable look in her eyes as she met his gaze. “I love you, BBBFF. And I know you love me. Not just as siblings, but as my lover. My stallion. We both know it’s true. Whether we admit it out loud or not. We can figure out how to deal with this later. Spike is even staying at the castle until tomorrow so we’re completely free. Right now, just love me, Shiny. This will probably be the one and only time we can ever just let go and enjoy being with each other like this without anything left to hold us back or worrying about what might go wrong. Nothing will change the fact that it’s all done for us already now. Let’s just continue with our original plan before we gave up the masks and spend the rest of our time here making love to each other. My apartment is closer and set apart. We can head there after we can separate and leave, then just talk this out there. M-maybe even let ourselves finish the plan we started, keep making love for most of the night and then talk in the morning, I-I don’t know. J-just…”

She began to tremble as she laid herself bare, her voice only a pained whisper. “I’m in full estrus, big brother. It might be too late by the time I can check and I’ll already be pregnant because of you. For now, just make love to me. Let go and share this perfect fantasy with me, like you’re trying to put your foal inside your mare because you’re the stallion I love with all my heart. Right now, I’m young and fertile and receptive and I need you. Shining, for both of us… Just this once…”

Staring up at him with pleading eyes, Twilight voiced her desperate desire.

“Breed me…”

Shining Armor felt his cock lurch inside his sister, his mouth opening and closing as he tried to argue, but try as he might to tell her otherwise, he found there was nothing for him to say. He wanted to deny it, to say she was wrong, yet between being trapped by malfunctioning spells and unable to avoid knowing he’d fallen in love with his sister that way too, the words of denial never formed. If it was just raw physical lust, he might have had the strength to resist, but he knew it was so much more than that. He swallowed the lump in his throat as his eyes misted, what few arguments he managed to think of were all crumbling away as his sister’s body, a mare he truly loved, tried to encourage him to release in her again.

It wasn’t long before his eyes softened completely, looking at the mare he had unknowingly fallen in love with, yet had also known and loved since the day she was born. He was trapped on several levels, admitting to himself that his growing level of arousal said he was indeed going to burst inside her again either way, then realizing he wasn’t even really resisting it anymore.

He realized his Twily needed him. She had needed her big brother to take care of her and help her with plenty of things in the past, and now she needed him to help her through her estrus. Her womb was needing more of his seed to calm, and she was begging him to give her more. If what he already gave her wasn’t enough, he would make sure so much of his essence was inside her that her estrus would be sated twice over!

Tossing the last of his resistance aside, he gave himself over to the only chance for this fantasy that they would probably ever have. Grinding against the still held open entrance of her deepest core with the head of his cock, he focused on the idea that his lover needed him to put his foal inside her belly, to satisfy her estrus by being impregnated by her stallion.

His lips pressed against hers as he pulled her in, slowly rocking against her as she gasped into his mouth. He felt her tremble and roll her body back against him in counterpoint to his thrusts, making it clear her body needed more of him filling her to calm her rampant need.

Twilight panted as she felt her brother give in and begin to thrust himself inside her core once more, her legs keeping a gentle grip on him. He could only withdraw himself from her marehood by an inch or so before the spell keeping their legs in position prevented him going further, then he slid himself back inside her to press against the open entrance of her deepest door.

She let herself stop caring that it was her brother inside her, even let it excite her further now, nerves tingling as she held him against her. The feel of his muscles moving in a steady pace, the sound of his breathing as her eyes fell closed as she let her head lay back. He was slowly rocking her back and forth with unhurried passion, and she reveled in the feel of it.

It wasn’t long before Shining began to flare inside her for the second time, causing Twilight to tremble in anticipation. When he thrust himself as far into her marehood as he could reach, she felt him start pulsing deep inside her, and more heat flowed past her cervix. She let out a squeal as it pushed her over the edge, the tightness in her womb growing a little as he added more to what was already contained within. Even in her oversensitive state after her climax, she whined in need as he began to move again and craving the intensity, the strength in his cock seemed to return even faster this time.

Shining pressed his nose to her throat as he worked his buried length in Twilight. It was a strange sort of state as he filled his sister again, yet needing to give her his love so much he couldn’t even stay still for very long after he came a second time. Drawing those soft gasps out of her mouth became his focus, her orgasimic squeals his constant goal. His forehooves held her in place so she wouldn’t slide forward, letting him push with firm strength each time he hilted inside her on every slow thrust.

The two of them strained together for one climb towards orgasm after another, with only Twilight’s own arousal free to escape and soak into the white silk bedsheets beneath them. As she had promised, every drop of Shining’s seed was kept locked deep inside her body.

Somewhere along the way, their lips met again and their tongues danced together in similar movements to their bodies, sweat earned in passion clinging to their coats. Their manes were soon damp and clumped together strands occasionally getting pushed aside from time to time. Even when they fell out of synch, they usually stared into each other’s eyes when one of them peaked, needing to see their lover’s pleasure as it happened.

When the chime sounded in the air, they finally found a reason to pause. Their four hour reservation had passed almost unnoticed, Shining making the last few thrusts to another plateau and giving Twilight another round of his seed for her still hungry womb. He relished the tired squeal that escaped her, feeling her insides twitch with each burst he gave her. Going still, he let her have some time to recover. It was just a ten minute warning for clients to know their session was almost over.

Twilight laid her head back as her orgasm faded, letting herself work on catching her breath again. She had lost count how many times her brother made her cum, or how many times he had cum inside her. The very notion of interrupting their shared passion to check if her magic was functioning again had been forgotten entirely until the chime sounded. Part of her wondered how he could still be pressed against her the same way, given how full her womb felt. A forehoof lazily moved down to the side of her stomach, partly just to feel her brother’s fur in another spot, and found her belly was tight, but did not seem to be externally swollen. A bit of pressure told her it was right on the edge of visible in the same way she might have been at three months pregnant. Having lost herself to the fantasy, it made her shudder and squeeze his cock again, feeling him twitch and signal his shaft was almost ready to start yet another round.

As much as she didn’t want to stop, she did realize it was necessary. She gave her brother a firm kiss, without tongue, before a helpless look came to her features. “Ok, let me fix the spells I cast that are keeping us stuck together first. I want to focus more before I try to do anything else. It’s really hard to focus on anything but you when I can almost feel your heartbeat inside me.”

Shining gave her a small nod, keeping still, and Twilight carefully drew on her magic.

A few seconds later, she fixed the two spells keeping their legs bound to each other’s body, then the one keeping her cervix held open against his tip. With a nod to him, Twilight couldn’t help the powerful shudder and gasp as his cock stimulated her nerves in ways he hadn’t been able to for hours. She was half-tempted to order him to slip back inside, already missing his presence more than expected, but knew they had to get going soon.

Before she could speak after the sudden rush of new sensations had passed, Shining’s hoof touched her lips and she looked at him in confusion, seeing him give her a tender smile.

“Twily, before you say a word, I want you to understand something… We can’t get today back, no matter what we do. Check the spells and fix anything that needs it, but don’t tell me what the truth is. If everything is actually fine, or if you’re already pregnant and there’s nothing to stop it now, we can deal with everything tomorrow morning.”

He smiled in a way that made Twilight’s heart flutter as his eyes misted. “Right now, I am going to take the mare I love back to her place. We are going to get some food together, then make slow love while we feed each other so we can keep our energy up. Then I’m going to spend the rest of the afternoon and most of the night trying to give my mare a foal. I am going to send so much of my seed into your womb that you will look eight or nine months pregnant by the time we’re done. I will see my mare looking beautiful with my foal inside her, or as close to it as I can get. To be honest, part of me is even torn on asking you to forget about the contraceptive spells entirely and keep yourself uncertain, too. To let yourself not know if it’s too late, or if the next time I breed you is the climax that makes our foal a reality. Do what you need to for yourself, but let me keep the uncertainty we can’t get back.”

Twilight stared at her brother, lungs heaving by the time he was done speaking as tears threatened to fall from her eyes. She smacked his hoof to the side and crashed against his lips with her own as she rose, giving her stallion a deep kiss. For a long moment, all she could do was hold still, lips pressed to his, struggling with her desire to simply pull him back on top of her.

Finally pulling back, Twilight sniffled and gave her big brother a shaky smile. “Alright then. Let me have a moment to check the things I need to and we’ll head for my place. We’ll have to go separately and I need to be waiting when you arrive. You could pick up some food and anything else you think we might want on the way. That would take care of everything we’d need to delay for.”

Seeing him nod, Twilight closed her eyes and focused on the spells on both of them. She removed the stamina spell on him, then the one that lined up their parts for him to have a straight path through her cervix. They could be recast later. She did take the time to cast something that would relieve the uncomfortable tension of her being stretched by what she kept sealed in her body, and the same spell would later allow her belly comfortably stretch as far as a full term pregnancy, if necessary. The more she thought of the idea, the more she needed to make it happen.

If they could only do all of this once, she wasn’t going to hold back on any of it.

Opening her eyes as she rolled off the bed and stood, Twilight looked at her belly and saw there was only the faintest visible sign of the mass of cum hidden inside her womb, as if she’d merely had a hefty meal. Her bags would make it impossible to spot on the way to her apartment. Her nostrils flared, eagerly looking forward to the two of them making it impossible to miss over the coming hours ahead. And that nopony but Shining would get to see her so completely swollen with her brother’s essence. Her nethers tingled at the thought.

And from knowing she decided not to check the contraceptive spells…

“Let’s get out of here, Shiny.”

Close to an hour later, Twilight Sparkle and Shining Armor had finished eating, the pair now in her bedroom and making use of her bed for the first time.

The time to calm and think a bit more left them deciding to just eat relatively quick at the table in a flimsy reach for the fantasy that they were living together, and it was just a normal meal with their special somepony. Neither really believed it of course, but both confessed it hurt knowing the morning meant it all had to end. Regardless of the possible results of how their accidental encounter brought them to this point, morning meant facing reality, and being forced to walk away. To try to forget they’d fallen in love and return to the normal kind of relations between brother and sister.

They admitted they weren’t sure how they could even begin to do such a thing and really hoping time helped.

Twilight stood over her brother as he lay on his back, staring up at her with a sly smile in the middle of her own bed. She had recast the stamina spell on Shining, but they both decided it would be more fun to leave it stuck on active again, rather than having it only function to reduce his recovery. The spell to align her cervix with his urethra shortly before his climax was renewed, then the one that would keep him hilted inside her when either peaked, though both spells would function as originally intended this time.

Aside from checking the integrity, she didn’t need to do anything with the one that kept his essence locked inside her still needy womb, much to her relief. She relished the knowledge that every last drop of of his virile seed was put inside her so effectively that her cervix was the first part of her body it had touched as Shining bred her multiple times earlier, the rest of her tunnel was still untouched by his cum.

A small shiver passed through her when she thought that maybe after she felt he bred her womb directly enough, she’d have him make a mess of her tunnel a few times as well. She only had this one time to let him ravage her in every way, after all.

She was even tempted to have him spray his seed over every single part of her body until she was nearly swimming in his essence, to let him mark her and claim her whole self as his mare alone. He already claimed her mouth, her plot, and her womb. Her heated stare bored directly into his eyes as she felt his tip touch the entrance of her sodden tunnel, only slight pressure was needed before the head slipped easily back inside her where his shaft belonged.

Twilight found she wanted her brother to know she owned his cock, and all the seed it could pour inside her. That no matter what else happened after they were forced apart, not one single mare after her would ever have more command of his arousal. And after an earlier confession he made to her as they shared their meal, Shining would know his former virginity on all levels was sprayed into her body. He would know his first time having sex was sealed by shooting his entire load directly inside his own sister’s receptive womb. She felt herself clamp down on his shaft, trying to coax him to give her more of his wonderfully warm, delicious cum as soon as possible. First, he’d fill her womb until she was thoroughly sated, and all but certainly impregnated with his foal. Then, she would swallow his length whole, make him completely fill her stomach with her new favorite meal as he begged her for more. And then she would slide him into her plot to cum deep in her bowels until…

“Uh, Twilight? You have a rather intense look on your face. You ok?” Shining spoke with a mixture of concern and lust, feeling Twilight’s marehood convulsing around him in a way that made it quite easy to perceive her estrus-driven needs. “You want to just skip dessert and get started or…?”

Shining watched his sister’s face explode with a blush so intense, he wondered if she was managing to change her fur color, her hooves coming up to cover her face as she peeked down at him, even as she continued to grind on his dick as it spread her open within. A faint squeak escaped as the closest sound to a response, though she couldn’t stop staring him in the eye and only seemed to squeeze her inner muscles even tighter.

Finally, after Twilight’s gyrations had grown enough she was likely moments away from starting to bounce on the length buried inside her, she managed to speak in a strained, lust-soaked voice. “We’re… Ah~! Going to get to, nnf… Dessert after you breed me again, Shining. M-my estrus needs more of you warming me up inside first… Mmm…”

With that, she let herself begin sliding up and down his cock, whining faintly and pressing her cervix against his tip with each drop of her body. Shining didn’t even try to reply as he placed his forehooves against her cutie marks to help her move with less effort. It wasn’t long before Twilight could feel his flare expanding, soon unable to do more than grind his tip against her deepest entrance, her spells activating to ensure everything he had would go right where it belonged.

She squealed and arched her back as the distinctive heat of his seed burned through her gate and into her core again, her tunnel squeezing and tugging like it was trying to draw his entire body in, coaxing more cum out of Shining. The sound of his gasp as he came inside her for the first time in her own room, on her own bed, their eyes locked on each other again, all of it came together to make her body shudder, her legs shaking as she collapsed on his chest, his last couple of spurts escaping his cock and entering her swelling womb.

A few errant twitches in her muscles aside, Twilight felt much more relaxed now and let out a content sigh. “Mmm… I needed that, Shiny. I… I’m letting myself simply give in to everything my estrus wants now, and wow, is it ever making me more turned on than I’ve ever been. I wouldn’t even object to you just spending the next several hours doing nothing but spraying cum inside me. Just letting you settle in on my back and not stopping…”

Shining Armor smirked, feeling his cock already reviving because of the stamina spell, even as Twilight was still getting over her orgasmic twitches. “If you want to do that, we can, but I know you wanted to spend time trying out anything we can think of before morning. Still want to enjoy some slow lovemaking as we feed each other the chunks of fruit in our dessert?”

Twilight quivered and nuzzled her brother, a content smile on her face. “I’d like that. Lay on your side with me so we can enjoy you sliding back and forth inside me without straining? I want to feel you cum inside me in every way I can.”

He let out a short laugh before catching her lips in a kiss, holding her close as he rolled to one side, keeping himself well inside her.

The two of them fed each other occasional pieces of fruit as they made love together, acting like lovers that had known each other intimately for years. With every climax they shared or gave to their partner, Shining hilting so his entire orgasm could be sent into her womb, Twilight’s belly swelled just a tiny bit larger.

The fruit was eaten along the way, everything else forgotten as they strained over and over, just seeking to give each other the next climax. It was a rare moment Shining’s cock was more than halfway out of her marehood, with most every shared peak only a few minutes apart.

As the sky was going dark outside, Twilight waddled slightly as she stepped into her shower, her brother right behind her. Her womb had enough of his seed inside that she looked around six months pregnant now. She cooed as Shining began to wash her, his attentions unhurried and intimate. They had no intention of staying clean though, fully intending to try lovemaking in the shower after they cleaned each other and some appropriate buildup. Soon, they eyed each other in the falling water, eager for the fun part.

“Do you like seeing your mare’s belly growing because of what you did, Shiny? To see me carrying your foal inside me?” Twilight’s voice was seductive, her wet mane stuck against her form as water ran down her body, posing for her brother’s gaze with a teasing smile. She relished every bit of their shared fantasy that she could get.

Shining snorted, giving her an amorous stare and grin as he broke eye contact to nibble along her neck and down her spine, earning a small whimper. “You look beautiful with part of me there inside you. So beautiful that I need to have you again. Right now. I need to make sure we’re ready to go again right after our foal is born. To put another one in your womb as soon as you’re receptive to my seed again. You love being my broodmare, don’t you Twily? Feeling my hot seed entering your womb during your estrus, knowing you’re all mine to breed…”

Feeling him nip her dock, Twilight let out a sharp gasp. “Yes~! Breed me again, big brother! Make sure I can’t forget who is the only stallion allowed to put foals inside me!”

Despite playing along with the shared fantasy they planned out, Shining was mentally laughing at the things they were saying, even as he used his magic to make sure her tail was laying along her back and trapped beneath him as he moved up to mount her. He could feel her shudder as the head of his cock found her entrance and sank inside, her marehood winking against him before he could reposition and thrust fully into her body again, the action drawing a moan from his needy mare.

For a moment, he just relished the feeling of being inside of Twilight again. The internal ripples of movement she made up and down his cock without even moving could probably get him to orgasm if he gave himself enough time. Standing there in the watery cascade of warm water falling over their bodies, he did his best to commit the moment to memory like he had done several times already. The feel of her head angled so he could nuzzle her cheek from behind, the way his forelegs were positioned around the swollen shape of her belly…

He kissed her cheek before his teeth found her ear and latched onto it, earlier experiments revealing it helped quite a bit to excite her even further. Then he began to make slow thrusts into her body.

Twilight made soft gasps as she felt her brother mount her with purpose, inner muscles clenching on his invading shaft when he growled in her ear and made a particularly firm thrust. Her eyes stayed shut as she felt her forelegs getting weak, feeling him get a little deeper inside her as she lowered her front half to the tiled shower floor. Even if she didn’t have spells for it, her position would have ensured everything he was going to give her would be kept deep inside. The position also sparked new feelings of submission. The feel of him thrusting down into her body and tapping her cervix was stirring her up more and more, knowing the feeling of him sending fresh pulses of semen into her womb would set her off hard again.

Feeling himself starting to flare, Shining increased his thrusts, making Twilight’s form shake each time he crashed against her to hilt his cock deep inside her body again. He rubbed his hoof over her enlarged belly, savoring the idea of her being full of foal. The uncertainty of not knowing if the next time he bred her could mean she might actually end up pregnant because of him kept sounding less terrible in his mind.

He knew a part of him loved her entirely as a mare, and wanted to fill her until his seed found her egg cell and ensured it was fertilized by him. As he panted and neared his climax, he told himself he wouldn’t stop until morning, to put enough inside her that her estrus would end overnight.

Shining used his own magic to play with her clit, pushing his cock as far down into her body as he could reach as his climax rose, even feeling her cervix kiss the opening of his tip, almost like her womb was begging to be bred.

Both of them came at the same time as his cum shot straight into her swollen core, their orgasmic cries mingling with the sound of the shower. Twilight’s squeezing passage encouraged him to fire numerous large ropes of seed inside her, adding more to the volume he had already filled her with. Every new position or method brought a new variation of climax, as well as leaving her just a little more sensitive than before.

Twilight found herself hoping her brother worked her into such a state that all she could do was cum on his cock and watch her belly swell with so much of his gift being locked deep inside. She thrilled in not knowing if the next time he burst inside her would be the one that ensured she carried his foal. To have the one she loved leave that kind of gift inside her. She demanded another dose of his seed before they had even finished drying off, squealing as he made her go off again, thrilling at the feel of more of his essence flowing into her.

On and on they went, straining together in various ways. Shining rarely slipped out of her marehood other than for position changes, and spent most of his time inside her hilted, teasing her cervix as he attempted to bring her another orgasm, while he built up the next one of his own.

By the time it was late into the night and they agreed on one last round of slower, more romantic lovemaking, Twilight had reached a point she looked ready to give birth any day now. So much of her brother’s seed was inside her bloated womb, she looked every bit as pregnant as their shared fantasy role play could have wanted.

Laying on their sides, spooned together as Shining made slow thrusts, Twilight experienced a modest orgasm every couple of times he hilted. Her marehood appeared unable to get enough, the constant winking against his shaft tried to press him against her inner gate and not let go.

Her hoof was holding one of Shining’s own against her swollen belly, her voice husky as she tried to drive herself onto his cock with each thrust he made. “Do you love knowing you put this in here, Shiny? That you put your foal in me even as you get ready to cum inside me again? You love impregnating me, don’t you Shiny? You love knowing your own sister only lets her big brother’s cock inside her body, knowing you came inside my womb and bred me, that I was begging for your seed to quell the craving of my estrus…”

Shining heard her let out a small whine as another orgasm rippled through her, feeling her marehood tugging at his shaft, her body still trying to pull even more of his seed into her. After staying hilted through her pleasured shudders, he went back to making slow thrusts as he drew back to his medial ring, then thrust back inside to the hilt and touching her cervix again, nibbling just behind her ear as he continued to work her over as he rubbed her swollen middle.

“I do love knowing you’re fat with foal, Twily. I love knowing how much of me is inside you, how much more is going to be inside you. And you love feeling me pouring my thick, potent, virile, seed,” Shining punctuated each word with a firm hump against her cervix, “directly into your fertile, receptive womb. You crave the feeling of me breeding you like a proper mare, don’t you? My own sister, so desperate for her brother’s cum to splash into her unprotected body, knowing I’m the only stallion you want when you’re in estrus. So desperate, you can’t stop orgasming on my cock and knowing you’re going to lose your mind when I burst inside your already pregnant body again…”

Twilight whimpered as she felt his thrusts drive her to another peak, but not stopping to let her ride through it now. He just kept filling her with his endless, slow, steady thrusts and making her orgasm last longer, her spasming folds trying to suck him in deeper. A nip at the base of her ear where she was particularly sensitive made her gasp, another orgasm already starting before the last one had finished.

Hearing a change in his breathing and his cock starting to swell, Twilight panted as she arched her back, trying to get more of his cock inside, hardly aware she was speaking as she rode a now continuous orgasm. “Yes, Shiny! Do it! Oh Celestia, g-get me pregnant!”

Shining growled, resisting the temptation to speed up his slow thrusts and feeling her constant spasms working at his cock in an effort to get his seed. His flare was starting to expand inside her and he knew it wouldn’t be long.

“Ah~! I don’t care anymore! I want your foal, Shiny! Rut your sister and cum inside me!”

Feeling the urge rising, Shining let himself give into the need and thrust with sudden speed, a smacking sound heard with each plunge inside. The rising volume of her voice and his rapidly approaching climax were making it hard to do more than deep thrusts, the head of his cock bumping firmly against her cervix each time. He just needed…

“I never checked the spells! Oh Celestia! Shiny, you’re going to impregnate meeee~!!”

He slammed his cock inside her to the hilt as he bit down on the back of her neck and mane, hooves pulling her down as his tip jammed against her cervix. His flare swelled just as Twilight’s spell made her womb open for the first jet of his cum to shoot into her, just as she said he was going to impregnate her.

Twilight’s voice devolved into a loud squeal as her last orgasm of the night hit her with force. The combination of her brother’s teeth pulling her mane and his spurting shaft inside her sent her careening over a whole new peak.

The feel of each other orgasming so strongly after many hours of sex left nerves raw and the experience feeling more intense. The two of them quivered and twitched as they began to come back down. Had they not already been laying on their sides, they would’ve fallen over.

When they finally recovered some of their senses, panting from the exertion, Shining hugged Twilight close, still keeping himself fully inside. A hoof ran lazy circles over her swollen belly, feeling her wiggle deeper into his embrace and letting out a tired coo.

His voice somewhere between sated and uncertain, Shining spoke in a quiet tone. “I guess you wanted the uncertainty too, eh, Twily?”

Her hoof pressed against the his on her belly, some of their reality starting to settle back in as she let herself enjoy the feel of him against her back and still inside her. “Yeah… For right now though, we’re going to enjoy today in every way we can. We’re going to enjoy falling asleep as lovers, BBBFF. Reality and consequences can wait until tomorrow, j-just this once…”

Shining nuzzled the back of her head with a small squeeze, hearing the ‘I hope’ she didn’t say out loud. Even he knew enough to realize it could mean the difference between her getting pregnant or not, if the contraceptive spells had malfunctioned or failed, but they both wanted it this way, knowing the risk of their fantasy turning very real with the light of the morning sun. “I really enjoyed getting to share all this with you, Twily. I’m also still your big brother. You are more important than anything this might potentially cost us. Even my career in the Guard, if it comes down to it. No matter what morning brings, I will still be here for you, ok?”

“I…” Twilight paused, taking time to think things over as she undid the stamina spell on him, then the two that made sure he’d put everything into her womb. A deep, calming breath put her worries aside for morning and she smiled, enjoying the incredible feeling of being so thoroughly sexually satisfied, a soft sigh of contentment escaping her lips. “Thanks, Shiny. Even if everything else falls apart, I won’t turn my back on you either. I wish we didn’t have those worries and could just be together, but it’s just not meant to be, I guess. At least we can always remember everything we did today as we lived out this fantasy, and most of all, sharing our first time together. Other than that initial moment of panic, I could spend the rest of my life trying, and still not have a moment that perfect again. Y-you made me feel complete in that moment, when everything was so overwhelming that all I could feel was you pulsing inside me, and all I could think was how much I loved you.”

Shining nuzzled against the back of her head again and gave her another small squeeze, then just held his Twilight against his chest as he used his magic to pull the bedcovers over them, previously shoved out of the way for their lovemaking late into the night.

“I love you too, Twily. Now I want to get some well-earned sleep while I keep my cock buried inside my well-bred, pregnant mare. The morning, and possible consequences, aren’t here yet…”