The air was heavy with the smell of their sin, of spent sweat and broken vows.

The last of their cries of passion had long since faded into nothing and now the only noise was their mutual labored breathing. Deep in their hearts, they both knew that what they had done was unforgivable and that in time they would be forced to pay for their crimes.

None of that mattered now.

"You're so like her… but so different." He whispered, his gentle breath making her ear twitch reflexively. He pulled her closer and ran his nose through her mane, still wet with saliva from where'd he'd bitten it in the throes of ecstasy. The cool night air blew in from the window and began to cool the frothy sweat on their coats, so she lifted the blankets over them with her magic.

"This… this was a mistake." She whispered, her voice barely audible.

"I know."

She turned her head and looked into his eyes. "This can't happen again."

He nodded.

"But it will happen again… won't it?"

Again, he nodded.

"How could we do this…?"

"Cadance will never know."

"But we will know. How can we face her every single day knowing what we've done? How can you?"

"We'll just have to."

"No. We… we have to tell her."

"What?"

"I…I… I shall take all of the blame. I will tell her I seduced you, that I… that I used my magic to make myself look like her. Just like Chrysalis did…"

"Stop."

"…something. She will run to my sister and she'll probably punish me but at least you'll be safe…"

"I said STOP."

The tone in his voice made her mouth slap shut. She saw his stern, commanding gaze and felt the indescribable shudder of pleasure in her belly he always made her feel. That was one of the things about him that had enticed her so; that way he ordered her around. All the lovers she'd had over the ages had behaved in her bed-chambers in much the same way as most ponies did on the streets; they bowed to her, prostrated themselves, and submitted to her will.

Not him though. He had an insatiable will to be in control and that was the one thing she wanted more than any other; to be controlled.

"We're not telling anyone. If they find out, they find out, but we won't go out of our way to tell them."

"…As you wish." Only he could command her like that and get away with it. She offered a secretive grin. "Perhaps I shall attempt to reveal our trysts in more… subtle ways then."

"How's that?" He asked, returning her smile warily.

"Perhaps I'll drag you away for prolonged…personal discussions. Perhaps I'll even entice you to take me on your marriage bed."

"Don't say things like that."

"And just how will you stop me, oh Captain of the Guard? Find a better use for my mouth, maybe?" She writhed against him, making sure to flex her wings against his chest, letting the feathers tickle him.

He grunted and squeezed her tighter.

She rolled her whole body over and kissed him, not frenzied as it had been earlier, but instead slow and sensuous. Her kiss was the kiss of ages, of infinite patience, of waiting, and of wanting. Her kiss was unlike any other he'd ever experienced.

And he loved it.

When again they parted, he pulled away, kicked off the covers, and slid off of the sumptuous four poster bed.

She whimpered in protest but did not follow. "Are you leaving?" She asked, using the new available space to stretch her legs and wings. "My sister will not return for hours yet."

He silently made his way to the dinner-cart and searched for a choice grape.

His ignoring her irritated her. "Or will Cadence miss thee?" She asked mockingly, slipping back into her ancient way of speaking.

He finished chewing his grape and selected another.

"We pity our poor niece. All alone in that big, cold bed while brave husband goes about with his night-watch duties. Dost thou think she minds?" She shrugged. "We don't. We trust that she knows that thou will do whatever thou must do to service… we mean in service… to the throne."

Still he ignored her.

Her temper flared and her eyes lit with the power inside her. "We know the saying is 'love is blind,' but dost love have no sense of taste? We wonder… does she taste another mare on your lips? Dost she know that other mare is her own aunt?!"

"ENOUGH!" He rounded on her, all muscles and willpower, and she stared him down, her ethereal mane blowing in the fierce night winds, the stars reflected in it flashing dangerously. Her wings lifted her from the bed and floated her across the room until she was face to face with him. He stared into the white pools of her eyes without fear.

"WHAT DIDST THOU SAY TO US?!" She threatened in the Royal Canterlot Voice, the tone making the walls shake. "THOU DARES TO TAKE THAT TONE WITH US?! AND JUST WHO DOST THOU THINK THOU ARE?!"

He refused to give her an inch, refusing to even blink. "I am Captain of the Royal Guard. I am in total service to the ruling sisters of Equestria… but I will not hear you speak of my wife, your own niece, in such a… a callous way."

Her eyes faded, the winds died, and she landed, leaning in close to his ear. "What you have done to her is far worse than anything I can say about her, my dear. Far, far worse." She turned from him and made to return to the bed. She felt his gaze on her swinging backside and sniffed haughtily. "Leave me in peace, Captain." She spat, heaping mockery on his title. "I have no further use of you this evening."

"No."

She turned in a flash to find him advancing on her.

"You have betrayed her just as much as I have, if not more, your Highness." He growled, soaking her title in just as much venom as she'd used on his. "So we find ourselves to be… co-conspirators."

"So we're just as guilty as the other?"

"Right."

"So it would be in our best interests if nopony were to ever find out."

"Exactly."

"Never?"

"Ever."

He'd backed her against the bed and she started as she felt her hindquarters strike the edge. "And just what do you have in mind to keep my mouth shut?" She whispered, her eyes narrow with uncontrollable lust.

His kiss was his answer… and she liked his methods.

/////////////////////////////////////////////

Neither of them was sure when the decision had been made to betray the ones they loved, but one thing was certain; the attraction between them had been instantaneous. Each could still remember that moment they'd first laid eyes on the other, when Cadance had introduced them early in their official court-ship.

For her, it was his eyes; how they pierced her so. Oh, he was handsome to be sure, but so were all of her past lovers. With him, it was… different. His eyes regarded her not as a goddess, but as another pony. An immortal all-powerful pony, but a pony all the same.

For him, it was the statuesque nature of her that stunned him. It was as though she'd been carved from some exquisite stone that absorbed the darkness around it. He knew her age, knew how many lifetimes she'd lived, and yet he was still amazed at her youthful appearance. He'd wanted to touch her coat, to see if it was as smooth and silky as it looked.

They'd never spoken of their attraction, never let on to any close confidantes about how they truly felt. Even at the wedding they'd done their best to keep their distance. It was only upon his return from the honeymoon that she'd first kissed him, a chaste greeting between two members of the same family.

Even in that momentary contact, they'd felt the spark that would soon grow into a blazing inferno.

That night, she'd waited and watched the door to his chambers from high up in her tower. When he'd ventured out for some nightly errand, she'd swooped down like some elegant bird of prey and bore him into the nighttime sky, melding her lips to his in a glorious display of pure lust. He'd responded in kind and in the long nights that followed each had revisited those fleeting moments of bliss. Their beating hearts and panted breaths haunted them, for they knew they could go no further.

In the end, it was he who had made the decision to give in to their feelings. He'd known the time had come when, while performing his husbandly duties, he'd imagined not a field of pink beneath him… but a starry sky at night.

/////////////////////////////////////////

Their bodies again sated, they lay together again, her head resting beneath his, their legs tucked beneath them. Their time together was nearly over, but they paid it no mind. They would savor every instant.

"What does this make me?" He asked, looking down at her. "Your concubine?"

She giggled, a light girlish sound that filled him with wonder and sadness; wonder at a goddess of her age giggling like a school-mare, sadness as he remembered how his wife had giggled like that when she was a school-mare.

"No, you are my… lover."

"So you love me?"

The fragile innocence of the question caught her off-guard. "…Do you love me?"

"I don't know. I love Cadance… but I just can't control myself whenever I'm around you. It's intoxicating. It's not like anything I've ever known."

"It is possible to love two mares, Shining Armor."

He kissed the top of her head. "But you are only allowed one lover, Luna."

"Yes… Captain." She paused, then added. "I've always had only one."

Shining Armor looked at her. "They died." It was a statement, not a question.

She nodded.

"Do you… remember them?"

"Of course. I mourned them each in turn… as I will mourn you one day, my sweet Captain."

Shining Armor averted his eyes. "Can we… can we not talk about that?"

She licked his cheek, realizing she'd upset him. "Of course." She snuggled closer. "We can just enjoy the stars."

///////////////////////////////////////

The time came for her to lower the moon and awaken her sister, so they said their good-byes and parted with a last kiss. The kiss was slow and they savored it, knowing it would have to hold them over for days, weeks, or even months until their next secret meeting. They only parted when she flapped her wings and ascended into the night sky.

He watched her until her dark form faded into the darker sky then quietly made his way back to his chambers. The sun was just starting to rise as he arrived. After peeking inside to make sure Cadance was still asleep, he crept to the closest bathroom and took a quick shower. After drying himself, he slipped back into the bedroom and carefully slid beneath the blankets.

His beautiful young wife opened her eyes half an inch and smiled. "Hi." She whispered.

"Hi."

"How was patrol?"

"…Exhausting."

She stretched and began to rise. "Would you like some breakfast?"

He caught her and offered a gentle smile. "Stay with me. Let's just sleep a little more."

She returned his smile and lay beside him once more, pulling his arms protectively around her. "Do you think that you could maybe talk to them about moving you back to day shifts?"

"Hmm?"

"I miss you."

The tone of her voice broke his heart and he clutched her tightly. "I'll ask, but you know how they are."

She laughed airily and started to go limp. "I love you."

It wasn't a lie when he followed her with an "I love you, too" in return.

Sleep came for Shining Armor and he reflected on how wonderful, terrible, and different his life was about to become. He had to be insane. Here he was, holding the most beautiful mare in Equestria in his arms… but earlier those same arms had been holding a goddess.

By the sun's light, he would love Cadence, bask in her glory, be kind to her, take care of her, and even one day have children with her.

But beneath the moon's milky gaze, love would give way to lust, trust would give way to deceit… and he would trade sanity for madness.

She was his madness.

His mistress.

His goddess.

His queen of the night.