i want an au where, after weeks of trying to adjust to caleb leaving for college, mc can’t seem to pull herself out of her downward spiral. she’s skipping classes and meals, becoming a social recluse, barely talking to anyone — not even josephine. so, she decides to pack a backpack with whatever she can carry, smashing her piggy bank in the process to gather all her saved pocket money, and takes the coelum express up to skyhaven

she’s terrified. she’s never been up there on her own before, and people keep staring at her, because she knows she doesn’t belong among them. still, none of it feels worse than the ache in her chest from being without her brother that won’t abate by the time she makes it from the station to the aerospace academy campus, it’s already raining, and she’s spent more of her savings than she would’ve liked. she stops someone she assumes is a student and asks where she can find caleb’s dorm, only to be met with laughter. “don’t we all want to end up in the heartthrob’s bedroom? keep dreaming”

she bites her tongue, as the comment hurts her more than she can explain. she’s his sister. the audacity of assuming she’s just another person trying to get with him! but more than that, the realization that there are, in fact, people who want her brother like that, is what has her digging crescents into her palms. of course they do. why wouldn’t they? he’s the sun. no wonder being knocked out of his orbit feels like her world’s been ended

the smallest your older brother has ever looked is when he’s laid out across your lap, lips wet in anticipation as he waits for you to unbutton the front of your shirt so he can latch onto your breasts and forget everything that’s been weighing on him.

lately, his missions have been longer and more taxing, stirring up chaotic dreams in ways even his prescribed medication can’t manage. so, you decide to help him the only way you know how. like this, still in uniform, with sunken eyes from countless hours of fighting off sleep and oxygen deprivation, the collapsed star-orange in his irises swallowed by an oppressive indigo, and his chin rough against the sensitive skin of your areolae, he insists he’s not himself right now, not caleb. you disagree. every version of him is yours to keep, especially the one that needs you to tether him back to his body he’s impatient tonight; a scratchy, rumbling sound forms in his throat as he mouths at your bra, and you can’t help but pat his stomach fondly, your hand already slipped beneath the hem of his undershirt. “bear it just a little longer, brother. i promise i’ll take care of you, okay?” with your other hand, you thread your fingers through his hair, scratching his scalp lightly, just to watch his thick eyelashes flutter from the sensation

luckily, the bra unclaspes at the front. you pause, one hand still in his hair, to remove the barrier once and for all, while the other slips out from under his undershirt and works at his pants, where he’s already visibly hard. guiding his face into your chest, you let him bury his nose against your sternum first. his whole body loosens when he inhales, then exhales. you’ve started wearing lactonic perfumes for this exact reason; they calm him down. his spit smears across your skin, but you don’t care. it’s the least you can do for your brother, who’s spent his whole life toiling endlessly for you. he trusts you to guide him when he’s vulnerable

guilt-tripping caleb into showering with you, then getting handsy when he comes home from skyhaven for his summer vacation. you’re home alone because josephine entrusted you to your big brother’s care before she left for the next city over to take care of “work.” you’ve never asked what this “work” entails, and she’s never told you; all you know is that you’re getting caleb to yourself, and you intend to take advantage of every moment — even if what you’ve planned makes you downright rotten to the core one day, as you finish up with dinner, caleb gives your leg a little nudge with his foot and nods his head toward the attic

“alright, pipsqueak. let’s go. i got the projector set up already — i thought we’d knock a few off the bucket list tonight”

you trail behind him up the narrow staircase, hands still warm from scrubbing plates under soapy water, and your stomach flutters the way it only does when you’re alone with him. the attic’s already been dimmed, and the standing fan that’s been here as long as you two have pushes the air with a cyclic whir-bzzt-whir. the couch pillows are stacked and slouched into a makeshift “nest,” and your brother’s laid out snacks, too

you move to flop down, but he lifts a hand before you can settle

caleb having you infiltrate the fleet once again because he needs eyes on the inside to prevent unrest within his ranks, especially with incoming personnel changes that will only lend him more power. you agree to step into a role you’re familiar with, his subordinate

the weeks go by with you reporting back to him in his office at the end of each day, relaying everything you’ve picked up on. but you’re getting bored because he’s neither your brother at the moment nor your lover. so, you decide to provoke him into abusing the authority he has over you as the colonel when he’s telling everyone to fall into line and barking out the day’s orders, you fold your arms and roll your eyes, which earns you stares from the people around you

“hey, do you want to die? why are you ignoring the colonel?”

at that, you snort and burst into laughter. “and what’s he going to do to me?”

realizing they might be implicated, the person talking to you quickly adjusts their posture, not wanting to be involved in the punishment you’re clearly looking for

telling caleb you have a surprise for him once he comes back home from work. he figures you’re just planning a more elaborate scene for when you get intimate tonight. he doesn’t expect you to hand him a black box that opens up to reveal a leather collar, a pendant hanging from its centre bearing his name. beside the pendant is a little bell that chimes with the slightest movement “i want you to put this on me.” you slide into your spot beside him, one arm wrapping around his back, the other guiding his hand to your “gift” for him. “when we’re at home, i’ll wear this for you, so you know exactly where i am at all times”