Rainbow plopped herself down at the lunch table, her broad and excited grin falling away when she only found Applejack there. She immediately started scanning the lunchroom, looking around in suspicion. “Hey. Where’s Sunset?” Even though the Principals had been quick to punish people who were harassing the former bully, Rainbow was still on high alert, and the absence of their newest friend didn’t bode well.

Applejack exhaled in a way that made her sound like an enraged bull. “She’s takin’ some make-up tests fer her classes, cuz o’ the bullshit with the locker an’ that webpage...” Hard green eyes glared around the room at people who refused to look towards their table.

Rainbow’s expression darkened into a scowl, feeling a mix of fury and shame. “...I didn’t know she failed tests because of it...” Her fist clenched her tray tightly—Sunset wouldn’t have had to make up those tests if they’d done their jobs as her friends. The athlete stewed for a few minutes in silence before she shook her head and broached the subject she’d wanted to bring up. “I wanted to ask you something AJ...You still have your bass from middle school? Because I was thinking, maybe you, me and Rarity could enter the showcase. Jam together like we used to—it could be super fun. I’m sure we could borrow a keyboard or something for Rarity.”

Applejack turned away from the other students to look thoughtfully at Rainbow. “…That does sound like fun. Ah still got it, but it’s in the attic. Gotta go find it. Sign me up, Dash. See if we still got it. Got anything we could play?”

“Oh do I!” Dash rummaged through her backpack, pulling out some pages. “Take a look at these!”

“Take a look at what, darlings?” Rarity sat down with her tray.

“Now that you’re in, I need to hit the music store this weekend to get a new guitar. You guys want to hang at the mall?” Rainbow Dash looked around the lunch table. “We could all go, then maybe get lunch or something.”

“I’d love to—there are some wonderful sales happening!”

Applejack rolled her eyes. “Ah’m in. Gotta pick up some things fer mah bass, anyhow. Ah’ll ask Pinkie in gym. Rares kin hit up Fluttershy in math.”

“What about Sunset? You think she’d wanna come?”

Rarity had taken a nail file to her nails. “You can ask her, Rainbow Dash, but she has always turned down weekend invitations. I think she must have some sort of weekend employment.”

“Eyup. That’s what I figgered too—bein’ from Magic Pony Land, she doesn’t exactly have family here ta stay with.” Applejack finished her cider. “She said she’s got a place ta stay an’ money fer what she needs, but that means she’s gotta have a job, an’ since she’s in school, that means nights an’ weekends.”

“I’m still going to ask her if she wants to go with us!”

“Sunset!”

The redhead almost leapt out of her skin when Rainbow Dash yelled her name, whipping around to face the much shorter figure, one hand over her pounding heart. “Dash! What’s wrong?”

“Nothing! I just wanted to catch you before you left for the weekend—see, I need a new guitar, since Rarity and AJ are going to play with me in the showcase, and AJ has to pick up some stuff for her bass too, and so we were going to make a mall trip tomorrow. They thought you might be busy but I wanted to invite you along in case you aren’t!” She grinned broadly at Sunset.

Blue-green eyes grew wide, and the former bully smiled crookedly at Rainbow. “You...you really do want me there?” she asked timidly.

Dash felt that flicker of guilt return, and she slugged Sunset’s arm lightly. “Yeah, yeah I do. You’re one of us, Sunset, and you belong with us when we hang. So...you wanna come with us tomorrow?”

Sunset chewed her lip, clearly warring with herself. “I would really like to, Dash, really...but I’ve already got a bunch of plans this weekend...”

At first, Rainbow thought that maybe AJ had been right—Sunset worked some kind of job to make money—but the way she looked nervous hit the soccer player like a jolt, just like she got sometimes when she puzzled out part of the mystery in a Daring-Do novel. After glancing around and making sure they were alone, she lowered her voice. “You know, Sunset, it’s cool if you’ve got another friend you’ve made plans with.”

The taller girl stared at her like Rainbow had just hit her in the skull with a soccer ball. “I...what? I never said—“

“Again, not dumb,” Rainbow Dash pointed out, before grinning even more. “Relax, Sunset. I get it. With how fucking shit we’ve all been, I don’t blame you for keeping it a secret.”

Sunset’s eyes scanned the hallway just as Rainbow’s had, before she answered, her voice unsure and wary. “You’re…not mad at me, are you?” she asked, and the sports star couldn’t decipher whether she meant about the friend, the secret, or the fact that she had other plans.

Smiling sheepishly, Rainbow stretched up a bit to sling an arm around Sunset’s shoulders, silently grumping at the fact that the height difference made it a difficult maneuver. “No way, Sunset! Whoever this person is, it sounds like they’ve been a better friend to you than we were for a long while, even with our promise to Twilight. The way I see it, I don’t have to know them to like them for being there for you when I was being stupid…and to know they’ve got to be a pretty special person.”

Sunset ducked her head, ears darkening as she stared at her boots. “….Yeah…yeah they are. I’m just…glad you’re not mad.”

Dash slugged her again with the arm not draped over her shoulders awkwardly. “See? There you go. You enjoy your weekend. We’ll see you Monday…and if anyone asks, I’ll tell them you had to work. Cool?”

The nervous half smile morphed into a beaming one, and Sunset turned the awkward position into a full on hug that Applejack would’ve been proud of. “Thanks, Dash. You really are awesome.”

Sunday evening, five girls sat around a table, drinking bottles of cider. “This has been the weirdest weekend ever....” Fluttershy murmured.

“You mean the most awesome!! I had wings again! I could fly! We have magic powers!” Rainbow punched a fist into the air.

“Ah’m not sure pony ears, hair extensions, wings that make ya look like a turkey buzzard, and forehead spikes count as ‘magic powers.’” Applejack sighed.

Rainbow Dash snorted. “Says you,” she countered.

“While I’d love the chance to accessorize, Applejack has a point. We really should discuss this with Sunset....I’m just very unhappy now that I realize none of us has her phone number.”

“Or knows where she lives! Ooo! Do you think she lives someplace neat! Like a house made of candy? I would totally live in a house made of candy if i ran away to another world!” Pinkie had stars in her eyes as she drifted into a daydream. “Oooo...if I ran away to a world that had candy houses, do you think the rain would be chocolate? Chocolate rain from cotton candy clouds....”

“Aaaand she’s gone...” Rainbow quipped. “Seriously though! Magic. Powers. How are you guys not excited?!”

“Magic transmutations that only last when we play musical instruments are not particularly practical or useful, Rainbow Dash. We could get the same effect with thirty minutes and cheap stage makeup.”

“Maybe we can ask Sunset tomorrow morning? She gets there early, right? Can we get the music room for lunch? Ask her to join us there? If we do have magic powers maybe she knows how they would work?”

“We all have a free period before lunch, right? Ah say we have Sunset join us then. We kin show her whats goin’ on. Rares, ya share first period with her, kin ya let her know? Pinkie an’ Ah don’ see her til gym.”

“I shall do my best, darling.”

Unbeknownst to the group, a few miles away a series of instruments recorded increases and spikes in an unusual form of energy they were tracking. It was barely a blip on the long record it had been keeping for several months, and it would take its owner a while to notice, but events had been set in motion that could not be undone.

“Sunset, the other girls and I were wondering if you’d be willing to meet us in the music room during your study period. We discovered something this weekend that we need to show you.”

Rarity’s words had been making her nervous all morning, a lingering worry that they’d found out her secret or discovered something awful about her eating at her guts like a nasty worm. Sunset pushed herself through her classes and now found herself trudging to the music room...though she was unbothered in the halls now at least.

Principal Celestia’s assembly had served its purpose, especially when coupled with a large swath of suspensions and at least two expulsions....not that anyone had been upset to see Gilda or Garble go. Since the previous Monday afternoon, people were content to simply stare at Sunset with dislike and mistrust, something she found easier to cope with than the constant notes and messages. No matter what anyone else said, she had earned that much negativity and still had a long way to go in proving herself to them.

Sighing, she opened the door to the music room, finding the girls there with a full band worth of instruments. “Um...what’s going on?”

“You know how I told you that Applejack, Rarity, and I were going to take part in the showcase?” Sunset nodded slowly. “Well, when we went to the mall Saturday, some stuff happened...”

“An’ yer the only one that might know what’s goin’ on an’ why its happenin’, since yer originally from Magic Pony Land..”

“Equestria,” she corrected automatically, before her brain backtracked. “Wait. Why would my being from Equestria help?”

“Because you’re the only one who studied about magic, silly!” Pinkie exclaimed.

Magic? She stared at them. “Uh...this world doesn’t have a lot of magic, girls, and most of it seems...ambient. Humans aren’t really made to channel what little is here—believe me, I tried to find a way when I first got here.” Sunset reached up to touch where her horn should have been, feeling the phantom sensation of her mind remembering the way the slightly curved spiral had felt as part of her skull.

“Um...I don’t think this magic is from here, Sunset,” Fluttershy offered. “It looks like the kind we used at the formal...”

“Yeah, before we shot lasers at you.”

She winced—the reminder hurt, her psyche still left wounded and sensitive by the events in question. “Are you saying you’ve found a source of Equestrian magic?”

They all exchanged a look, and Rarity adjusted her keytar. “It might be better if we just show you. Ladies?”

“Right! Just like we practiced, yesterday! Count us off, Pinkie!”

“One! Two! Three! Four!” The sound of instruments—not quite coordinated, with their users still finding the right rhythm and harmony with each other—filled her ears. The song was upbeat, in a ‘rock-pop’ kind of way, one that Sunset thought she could enjoy if the group got in more practice together. It made her own fingers itch to be holding her own electric guitar—she could hear the blank space where a rhythm guitarist would complete the music.

Then she felt it, the same building pressure in her skull where her horn once was, though it registered as more uncomfortable than painful this time, her latent magical senses screaming to life. In the last few weeks, she’d thought she’d caught hints of magic, but this was undeniable. Her breath caught, as energy as familiar to her as her own mind, yet somehow infinitely and unmistakably alien, resonated from her friends, before the pressure bubble popped, and they changed before her eyes.

A tremor of fear made a shiver roll over her entire body, and she scuffed her foot as part of her screamed furiously for her to flee. Instead, she tossed her head, straightening her shoulders and refusing to look away as wings unfurled proudly from Rainbow Dash’s shoulders, flaring with all the bluster of a preening Wonderbolt before swooning fans, or when Applejack’s ears pushed her hat back when they took up residence on top of her skull, absently twitching. She forced herself to watch, masking the pained envy in her eyes as a beautiful, perfectly symmetrical spiral of white came into being on Rarity’s forehead.

The same part of her screaming that she run away tensed up as the energy grew outward in a gentle wave, expecting more pain. None came; instead she felt...light, happy...it was like a tingling magical hug, one that filled her with energy and vigor. The remaining ache in her head vanished—she could still feel the magic, but it no longer felt like her head was being squeezed.

Sunset motioned for them to keep playing, moving cautiously closer as she reveled in her magic sense working right again. There were layers to the way this magic felt, and she inspected each of them critically, making hand gestures to request permission to touch the new and transformed parts, starting with Pinkie’s ears—AJ would have been easier, but she wasn’t sure she wouldn’t offend Rarity, so Pinkie was a better choice.

The ears twitched under the pads of her fingers, their poofy haired owner giggling. “That tickles! Do it again!” The ears rotated and moved on their own, seeming fully capable of the full range of motion of any pony, though a human lacked the instinctive knowledge of pony body language to make much sense with them. In fact, Pinkie was sending her brain all manner of weird mixed signals with her ears, and she shook her head, backing off.

Next came Fluttershy’s wings—Rainbow was busy creating a new meaning for the phrase “air guitar” and was out of reach. “May I?” She asked with extreme politeness—with pegasi wings being almost as personal as a unicorn’s horn, the words of Princess Celestia that had been ingrained from a young age echoed in her mind and governed her actions.

“It's important you don’t grab strangers' wings without permission, my little sun. You would be uncomfortable if they touched your horn without asking. Now apologize to General Thundercloud, please...”

Fluttershy gave her an uncertain smile, but carefully extended one of the wings folded close to her back, turning her head to admire the glossy feathers. Sunset did a quick feather-count, hearing Celestia’s voice naming and numbering them in her foalhood. They matched the shape, arrangement and count of pegasi feathers, and she could even tell which type of pegasi bloodline they came from (a fascinating and lingering effect from the three tribes era that could be found in all the tribes.) She kept her touch gentle as she felt along the pinions and the wing bones, all the way to where they appeared to phase through the material of the shy girl’s shirt, speaking in the same gentle but firm tone she’d adopted for dealing with Twilight’s anxiety attacks, detailing her actions before she took them, giving Fluttershy the option to pull away. In the end, she held a single flight feather in her grip, showing it to the girl it belonged to. There was no mistaking it for a normal bird’s feather, being that it was easily twice the size of those of the largest birds on record in the human world, with a shape and texture that was far too soft for normal birds to use in flight.

Finally, as the song looped for the third time she approached Rarity, looking deliberately at both her and Applejack. “Rarity,” she began awkwardly, “under any other circumstance, I would not even consider asking this, but...may I? I want to assess how similar your horn is to a real unicorn’s...” she faltered, eyes going back and forth between the pair, feeling heat rise in her cheeks at how uncomfortable this was for her.

Rarity seemed puzzled for a long moment, taking in Sunset’s behavior. “Of course, darling. You are our resident magical expert, so I don’t consider this an invasion of space,” she began, then paused to look at her more searchingly. “Though I’m getting the impression that this has more...personal and cultural implications for you?” Her voice lowered so only Sunset could hear.

Hoping to get this embarrassment over quickly, she prodded the forehead area around the horn with her fingers. “Extremely. Unicorns don’t let just anypony touch our horns, even other unicorns, not with hooves or magic.” She focused on repeating it the way it was explained to foals. “It’s not only incredibly invasive, it can be dangerous if it’s grabbed by another unicorn’s magic. Letting somepony else touch our horn is...it’s incredibly intimate and usually reserved for romantic partners—or parents with their young foals.” Her cheeks felt like they were permanently red now, as she inspected the perfectly symmetrical spiral (there was something unfair in a human getting such a perfect horn, when even the Princess owned a hornfile to smooth the occasional blemish.) A fingernail tapped against the center of the horn, listening to the way the keratin sounded against it.

“Ah. I can understand why this discomforts you, but I assure you Sunset, I do not consider your actions a violation of my person, given you asked and I lack the cultural background to see this as taboo. Although...that does feel odd. Can unicorns feel with their horns? I would have assumed it more like fingernails or hair.”

Sunset put pressure on the end of the horn with two fingers, gauging Rarity’s reaction and trying not to drown in embarrassment. “To an extent. The outer layer is comprised of a material not unlike the keratin found in our hooves or your fingernails, though it’s a much better magical conductor. It's the core that is sensitive—it's an extension of our skull, and the center of the core is essentially a nexus for all of our internal magical pathways.” Talking arcanobiology steadied her nerves and she found herself more at ease as she noted the length and growth patterns of the horn, matching it to Rarity’s age and lifestyle as a human, and, like with Fluttershy’s wings, picking out markers consistent with certain unicorn lineages. “The outer layer grows a little each day, mostly symmetrical and even but a lot of us keep hornfiles to even out rough edges on the spiral. The core only grows until we reach adulthood, and there’s some speculation among both the aristocratic and academic circles about the correlation of horn core size and shape and its affect on magical power—or there was before I left. That bit of nonsense mostly came from from the the unicorns with their horns up their own plots about how great and wonderful it is that they can trace their lineage back to Princess Platinum or one of her court.”

Distracted by her brief rant on the classist ideals of Canterlot unicorn nobles, her fingers ran over the base of the spiral and Rarity jerked her head away with a squeak of surprise. Sunset immediately recoiled, cringing and apologizing. “Sorry, sorry! I didn’t know if it would be as sensitive, I should have warned you!”

Rarity exhaled a shaky breath, smiling encouragingly. “It’s quite alright, Sunset. No harm done. I just wasn’t expecting...that…particular reaction...”

“...yeah...well now you know why we don’t go around messing with each other’s horns like that unless said unicorns are intimately involved...” she grumbled, her threshold for the situation far exceeded.

The music stopped, and within a handful of heartbeats, the transformations melted away and the magic faded into the aether. Sunset took the time to study the feather still remaining in her one hand. “Hm...not basic aura manifestation then, or any kind of illusion.” She offered the feather to Fluttershy, and the girl took it.

“So? Are these powers awesome or what?” Rainbow asked her with glee. “I think they’re totally badass!” Applejack swatted her with her hat, before looking back to Sunset, who was chewing on her lip.

“It's....not entirely Equestrian magic. Part of it is—your ears, horns, and wings are perfect matches for all three tribes, and it...feels like home, but it’s not the same. It’s those other parts that I don’t quite get...” she sat on the piano bench nearby. “And without my horn I can’t run complex diagnostic spells—all I have to go on is my inherent magical sense, and as good as it is, it’s a poor thaumometer under even the best circumstances.” She rubbed her thumb against the center of her forehead again. “I miss my horn...” she muttered.

“You can sense magic?” Fluttershy took a seat beside her on the bench.

Pinkie bounced over as well. “What does magic feel like? Like touch? Or a smell? Or a taste? Ooooo! Does a magical rainbow laser taste like Skittles??” She grinned. “Does everyone’s magic taste different? Does mine taste like candy? Or cupcakes?”

Sunset stared. “...ooookaaaay...” Sometimes the pink one was just too much for even her brain to handle. “It's not...like any other sense. It’s...it’s like a taste and a smell and a sound all at once, sort of fused together, and the different kinds of magic feel different.” She sighed. “It’s an ability found in unicorns, though most only have it in a rudimentary fashion. Those of us who studied magic extensively have to refine it, but even then we tend to rely on spells for more complex information and analysis.” She spread her hands helplessly. “I can’t tell you what is going on...though it doesn’t seem to be a danger to you. None of you feel any pain with your transformations, do you?”

When five heads shook at her, Sunset tapped her chin thoughtfully with one finger. “Then for now...I can observe? Maybe come up with some tests I can run? I might be able to design some kind of thaumometer...I also recommend keeping this to yourselves for now.” Her mind flitted back to Twilight mentioning her instruments picking up energy the night of the formal.

“Alright! That means we can still play for the showcase and come with cool special effects! The Rainbooms are in business!”

“The Rainbooms...?” Rarity asked archly.

“Yeah! Its the name if the band!”

“How come we didn’ get a vote, Dash?” Applejack rolled her eyes. “‘S our band too.”

“Cause it was totally my idea! And we used a rainbow that exploded to take out a demon!” Rainbow realized a moment too late what she had said, and she had the grace to look sheepish. “Uh...no offense, Sunset.”

It had felt like talons across her soul, and she looked away to hide the hurt. “None taken,” she responded. “You aren't wrong.” Fluttershy gave her an encouraging hug that took some of the sting away.

Applejack sighed. “There was one other thing, Sunset. We couldn’ get ahold o’ ya this weekend when everythin’ happened, even though we wanted ta. Realized a little too late that ain’t none of us got yer number. Ya willin’ ta share it with us? Then we kin get ahold of ya when we aint in school, an’ it means we kin invite ya along ta stuff when we decide ta do them all spur o’ the moment.”

The last of the hurt faded away, pushed aside by a pleased sort of happiness. “Oh! Sure!” She rattled off the phone number for them to save, and soon her phone was vibrating away in her pocket, giving her five new numbers to add to her contact list—more than doubling the number of the people she deemed important enough to have their numbers on hand.

I didn't really feel the need to rehash all of the "initial music based Pony-ups" shorts in a chapter, given that it would have felt redundant, and I'm well aware that the bulk of the audience is familiar with them, at least in passing. So I prepped some lead up and did the aftermath--with some creative finagling to make it all happen with her offscreen, because the one super telling thing in the pre-rainbow rocks shorts is the deliberate lack of Sunset in any of them. They went out of their way to downplay or avoid any mention of Sunset in the promo materials, and I suspect it was extremely deliberate, because it makes the plot have more punch. Makes that reveal at the end with her that much more powerful a story climax.

Trying to also sneak in a little of the world building periodically without it being "wall of boring exposition", because no one wants to spend 10k words in a chapter of me detailing how I'm working out pony culture.