Based on that one teaser for 3b – TW for implied self harm and suicidal thoughts

It started small and quiet, like a tumour that you don't notice until it's too late. Just losing time – little bits here and there – zoning out in Economics and coming to in English – not unheard of. Then Stiles notices his hands shaking after practice and he can't get them to stop, so he shoves them into his pockets and gives Scott a nod over his shoulder instead of a wave. He nearly hits a tree on the way home. His dad would kill him if he ever found out. He doesn't remember falling asleep that night, but hey, that's pretty normal, right?

A week later and his dad's giving him those disappointed eyes and imploring Stiles to spend more time at home with him. Stiles gives him a twitchy smile and a promise, but when he gets upstairs he has to stop and bend double to breathe because he swears to god he spent just last night curled up with his dad in front of a game.

The opposite happens with Scott a few days later – Stiles comments on the awesome Call of Duty session they had last night and Scott tells him he knows they haven't played in weeks but there's no need to be snarky about it. Stiles excuses himself and throws himself into a bathroom cubicle in time to retch up all of the nothing he's eaten that day.

He has a dream Peter bit him and he swears he can feel the pull of the moon. He jolts awake in front of his computer screen where he's got the beginnings of an essay written up, the rest of the page full of 'PLEASE PLEASE PLEASE' typed over and over. Stiles lets out a single terrified sob before slamming the lid of the laptop and curling into bed.

He still hasn't managed to get his hands to stop shaking.

Scott apologises for keeping him up last night, he just really had to talk to someone about Allison, you know? Stiles brushes it off, but his knee is jerking violently under the desk and he didn't even know Scott was acknowledging Allison's presence again.

His dad's disappointed again when he gets home – he got a call from school saying Stiles has missed most of this week. Stiles can't keep his hands still so he twists one in his shirt and the other in his hair and tries to look contrite while his heart's trying to beat its way out of his chest. Next thing he knows his vision is blurring and he can't– he can't fucking breathe– oh god– dad- but he's alone in his room and oh fuck he's going to die and he can't leave his father like this he just can't. It's the bang of his window as it slams open that startles him out of it, then there are warm hands on his face and sea-green eyes roaming over him. They're brimming with concern and the hands are almost tender. Stiles just blinks dumbly up at Derek's face when he asks him if he's okay. I can't lose you, I just can't, Derek says, and Stiles just doesn't understand when Derek brushes dry lips against his temple, undresses him, tucks him into bed. He doesn't understand why the flashing clock on his nightstand says the date is the 23rd of November either. He makes a mental note to fix it in the morning.

It's dark and his head is thudding and the whole sweaty room seems to be heaving and there's a flick of dark hair and a sweet voice asking if he wants to get out of here and yeah, he really does.

Coach is yelling at him that he's off the team because he's missed one too many practices this time, Bilinski, and Stiles doesn't even register that's not his name. That's the first night he sees his mother. She's dead. He knows that. But he sees her die so many times that next week that he can't be certain. Sometimes she mauled before his eyes, flesh slashed by unseeable claws, blood gurgling in her throat. Sometimes he can see the illness growing on her, feeding off her, making her thin and weak and pale until she simply fades away. Every time, though, while he's screaming at her and crying and trying to warn her, she just smiles serenely. It's okay, baby, she says. Stiles feels like those claws are ripping into his own chest, but when he looks down, he's whole.

He doesn't feel whole.

He wakes up with blood sticking to the sheets and-

It's just me, Derek says as he materialises in Stiles' room and nearly gives him a heart attack. He climbs into bed behind him, clutching him close to quell his trembling. Wh-what- Stiles says. Aren't you used to this by now? Derek asks with a chuckle. Stiles convulses. You're not well, Derek whispers into the back of Stiles' neck. Stiles bites his tongue till he tastes blood and pretends he's fallen asleep.

Someone sits with him at lunch – a girl, pretty. He doesn't know her.

Something in his head clicks and he sees Ms McCall cowering in the corner of the kitchen clutching a baseball bat in front of her. Scott's not home, she says. Please, she whispers. Stiles drops the kitchen knife with a clatter and closes the door gently as he leaves. He doesn't go home that night.

He's wandering round the edge of the reserve when a cop car pulls up and his dad's deputy Tara's pulling him into a hug. Stiles, she says, it's been weeks. Your dad'll be so reliev- shit, we need to get you patched up. Stiles looks down numbly at the steady stream of dark blood dripping from his fingertips onto the frost-covered forest floor. Bile forces its way up his throat to join it.

He can't wash the taste out.

There's the sick, sterile smell of hospitals in the back of his throat and he sees his dad asleep in the hard plastic chair next to the bed. He blinks and it's him in the chair, feet swinging inches from the ground, staring hard at the floor, the clock, anywhere but the dead-looking form of his mother on the bed and wondering where his daddy is.

His daddy cries when he wakes up, scared to hold Stiles' hand in case he disrupts the stark white bandages up his forearms, whispering that he's so sorry, that maybe if he'd been home more, if he's noticed earlier, if Stiles had just said something …

Stiles can't hear him over the roaring in his head.

He wakes with his head cradled in his hands, clumps of hair and streaks of blood marring the white sink he's hunched over. He screams.

He remembers when his mother's hair started falling out, so she shaved it all off and wore pretty scarves instead. Stiles had cried and cried and then said he wanted to do it too. His mother cried too, then.

Stiles feels soft hands on his scalp and hears the soft murmuring of his father's voice. It sounds like a home he has to run miles and miles to get to.

He runs.

It's snowing out, the metal slippery and burning cold beneath his trembling fingers. The window bars are stiff with ice, but determination makes him strong and Derek never did bother locking the windows. Stiles' sneakers skid a little on the window ledge. He can hear the cars rushing by below him – they look like toys. It's okay, baby, his mother says, come home. Come home to me.

The cold makes everything sharp, clear-cut like it hasn't been for months and months, and over the rushing of the wind and the rushing in his head he hears the sharp intake of breath behind him that turns into a growl almost instantly. Stiles, Derek's voice is closer now, but still inside – he can't open the window without knocking Stiles off. The snowflakes fall down down down and Derek is speaking low and earnest, the edge of desperation making Stiles' toes curl. Stiles you don't know what you're doing, Stiles you're sick, Stiles I can help you, what about your father, Scott, me, Stiles Stiles Stiles- Stiles closes his eyes. It's okay, he says. I'm going to fly. I'm going to fly all the way home.

Stiles' mother smiles at him, and he joins the snowflakes.