Vanya stays.

She stays through Klaus taking off in the middle of the night, fear making his eyes wide and his teeth splitting his face in a grin too large to be nice. She stays through Allison gathering her belongings neatly into a shiny new suitcase and stepping into a taxi to the airport without a glance backward. She stays through Diego's last tantrum and screaming match with their father and the door slamming so hard their family portrait is knocked off the wall.

Luther is left alone.

Vanya stays through it all.

Luther doesn't know why Vanya sticks around. He knows why he can't leave, sure. It's simple: he has been raised to save the world. He cannot resist his calling, even if their siblings can shirk their responsibilities so easily. He's a hero. He's here to keep being a hero.

Vanya, though. He feels bad, a little, to call her nothing, but that's what she is. She has nothing here. Staying is useless.

She stays anyway.

It goes like this: The mission alarm goes off when Luther is downstairs trying to distract himself from how big the Academy is. He goes upstairs and gets dressed and stands before Dad and is told what he must do. He goes. He saves the day. He comes back.

It goes like this: Vanya is playing her music and stops for the alarm. She watches from the doorway as Luther leaves. She waits for him when he comes back and makes him eat something. She leads him to Mom and helps patch him up. She places a palm over his forehead and pushes his hair back, every time, and looks in his eyes.

They go like this: "You did good," Vanya says. She says this every time. She makes up for where their father lacks. Luther doesn't look her in the eyes and he nods and he goes to bed.

They don't go like this: Luther tells her what happened to him, the kick in the chest or the gunshot near his ear or the hands around his throat. Luther apologizes for the ache behind her eyes, in her music. Vanya hugs him. Luther asks why she stays. She smiles and he smiles and they are fine.

Vanya stays and plays her violin and it is sad, now, with the emptiness of the house seeping into her music. Or maybe it has always been so sad and Luther simply never noticed.

She plays and plays and plays and when he gets angry and yells and tells her to just go, to get out and don't come back, she stops. She waits him out when Luther rages and asks her why she thinks she'd be useful staying here. She waits him out when he tells her she'll never be a hero. She waits him out while he shouts that she was never part of this family.

She plays and she waits and when he's done, wrung out and empty, she makes him a fluffernutter sandwich.

He only ever throws that tantrum the once, three years after everyone else left. The next morning, Luther wakes up to the strains of Bach floating through the air and stares at his model planes and cries, just a little. The tears sting at the cut on his temple, the one preventing Dad from placing his wires there like he thinks he's clever.

Luther doesn't know who he's crying for.

Their father hates Vanya with more passion than he is capable of in any other venture.

They don't talk about it.

They go like this, one night: Vanya applies to the New York Philharmonic. She gets a call back. Father slaps her and she falls.

Luther's throat closes up.

They go like this, one night: Luther finds her in the wee hours of the morning, slumped in a tiny huddle in the corner of the hallway. She is wearing a sweatshirt that used to be Ben's. It is too big on her. She is crying.

They go like this, one night: Luther sits beside her and tucks his legs up to his chest as best he can. Vanya doesn't look up. She sniffles and Luther doesn't know how to help.

"I'm sorry," he says, and Vanya shakes her head.

"It's not your fault."

"It is," Luther points out. She looks up, face red and blotchy and he shrugs. "A little bit."

"Maybe a little bit," Vanya says after looking at him for a long time. She looks away, at her hands curled in her sleeves. She sniffles again. "Thanks."

"Please don't thank me for not being a shitty person," Luther says. It startles a wet giggle out of her.

Nerves make his hand shake when he flips his palm up, knuckles gazing the hardwood floor. It takes a moment, but Vanya fits her palm in his. He marvels, for a while, at the differences.

Her hand is thin and pale and cold. Her fingers are calloused like his, but he has a kink in his right pinkie knuckle where Diego broke it when they were ten. Her bones are defined and fragile and not useless at all when she fills her hands with music. Luther's are useless without something to punch. Her hands are important; his hands are perfunctory. Tools of the trade, both.

Vanya has always reminded Luther of a bird; she flits and flutters at the edges of his life, never quite able to settle down. She makes sweet music but cuts off at the first sign of movement. Her bones are so very delicate. He's watched, for years, as her face sharpened under their father's unrelenting thumb, as her cheekbones threatened to break through the paper-thin surface of her face, as her knuckles grew more defined and less pretty as a bird's wings. Luther wishes, sometimes, that he could take her bones in his hands and smooth out her sharp edges, rub away the hollows in her cheeks with his thumbs, gentle some kind of warmth back into her skin. The cold set into them both a long time ago, but Luther is willing to help her fight it off.

They go like this, one night: "Why can't I be good enough?" Vanya asks in a voice too small.

"I don't know," Luther says honestly. "I'm sorry. I don't know."

They go like this, one night: The bruise under Vanya's eye darkens with the passing hours. Her hand stays in his. Luther could break her fingers with a single twitch and ruin her life forever.

She holds his hand like she has nothing to be afraid of.

Luther gets hurt; chemicals burn into his chest, his thoughts goes hazy, he barely makes it back home before collapsing on the front steps. The last thing he remembers is the fear in Vanya's eyes as she leans over him and mouths his name.

He wakes up later-much later, apparently- and Vanya is there. Vanya stayed.

It's been weeks, she tells him. She gave him her blood so that their father could save his life from the chemical burns, she tells him. He's lucky she's around because the only other option was Pogo, she tells him, laughing. They share blood now, like a real family, she tells him, smiling.

She doesn't tell him what their father had to do to save his life. She doesn't tell him how she survived their father without him. Luther doesn't ask.

She holds his hand in hers and pushes her own warmth back into him.

Maybe Vanya isn't the one who needs saving, Luther thinks to himself, and holds her hand just a little tighter.

"It's the new dosage," Vanya gasps. She breathes harshly, in-out, in-out, in-out, into the toilet bowl.

Luther doesn't know what to do.

Vanya's hair is very long. Luther hesitates, but Vanya leans fathering into the toilet, groaning, so he reaches out and threads his fingers through her hair. He pulls it off her neck with a gentleness he's only now learning. The nape of his sister's neck is soaked with sweat.

She hacks dryly into the bowl twice, says, "I can't-" and vomits again.

Luther waits her out. He's learned more about patience in the past few years than he ever knew.

"What's in those pills, Vanya?" Luther asks.

Vanya doesn't seem to hear him. She shakes her head, coughing, wipes her mouth with the back of her hand. He is struck, again, by how very small she looks. "It's fine, I'm just not used to the new dosage. I'll get better in a few weeks, when I've been taking them for longer."

"Vanya."

She looks up and her eyes are wet. It's suddenly a little harder to breathe.

"What's in the pills?"

Vanya shrugs helplessly.

Luther goes to Pogo. Father is locked up tight in his study and Luther feels the skin on the back of his neck prickle at the thought of cameras watching him as he enters the library.

Pogo is sitting quietly beside the fire.

"Pogo," Luther says. He waits for Pogo to jump and clutch at his chest and then settle down. Luther does not take a seat when Pogo offers it.

"Can I do something for you, Master Luther?"

"What's wrong with Vanya's medication?"

Pogo shifts. Luther's teeth grind down hard. People think he's so stupid, but it is very obvious this is not what Pogo wants to talk to him about. Which means it is what Luther needs to know.

"Miss Vanya has always been very nervous even as a child, and your father-"

"I didn't ask what was wrong with Vanya." Luther says. "I asked what was wrong with her pills."

Pogo goes still. His face is different from a human's, but not enough for Luther not to notice guilt. "Pogo."

"Your father only wanted to help, Master Luther. The consequences of Vanya going unmedicated-"

A memory flashes in Luther's mind, unbidden. Vanya, playing the violin when they were twelve, fingers clumsy, missing more notes than she hit. Vanya, at sixteen, her medication upped by their father that afternoon, speaking at the dinner table like her tongue was too thick for her mouth. Vanya, at twenty-two, dazed and confused when Luther found her in the garden in the middle of December without a coat on.

Vanya's hand, so thin and fragile, hollow bird-bones in his meaty palm.

Pogo speaks of powers going unchecked and adolescent aggression and fear and control like a professor giving a lecture. Vanya is sleeping off the rest of the drugs upstairs. She doesn't have to know what Luther knows.

Luther has heard enough.

His sister looks up at him with a bleary gaze when he shakes her awake. She's slept for several hours. It's the middle of the night. She wants to know what he's doing here.

Luther almost shoots the question back at her, used to wondering about it by now. He doesn't ask.

"If I told you a secret that would ruin your life," Luther says instead, gripping her shoulder firmly, gently, "would you trust me to keep you safe?"

Vanya is awake now. Her face has always been so serious.

She thinks about it for a moment. Luther waits. Father's study was surprisingly easy to break into; the doorknob wasn't even reinforced steel. Dad's journal is tucked into the backpack Luther took from Klaus's old room, strung over his shoulder and comically small.

They don't have a lot of time.

Luther waits for his sister anyway.

"Yes," Vanya decides.

It feels like something unclenches in Luther's chest.

"We're leaving," he tells her. "Only the essentials. We're not coming back."

Vanya looks at him. He asks her to hurry.

She does.

"Why did you never leave?"

The question burns his throat on the way up. Luther has been wondering this for a very long time, but as things got worse and worse, he couldn't quite make himself say it. He doesn't think he really wants to know.

Vanya looks out over the rooftops. The city lights reflect in her eyes, big as dinner plates. She's still not alright. She may not be alright for a very long while. Luther takes her hand and she laces their fingers together. She doesn't look away from the skyline. Dad's journal sits abandoned in her lap, open to the last damning page. Luther is glad Allison is across the country right now.

The sunrise reflects in the tear tracks left on his sister's face. He doesn't try to wipe them away; sometimes, you need evidence of your own suffering.

The rest of her pills had rattled in her pocket when they got into the car. He wonders if Klaus could help her kick them. He wonders what she'll look like, a Vanya with powers. A Vanya with feelings.

But that's not quite true, is it? Vanya feels more than Luther could have ever guessed when they were children.

Luther looks out at the city too. New York seems much larger now.

"I didn't want to leave you alone."

Luther closes his eyes. It is easier to breathe out here.