"Um, maybe? I felt really sick but it's gone now. But I don't know where... I am?"

"This is the Scholomance. Magic is real, wizards send their kids here if they can, because the Scholomance has a survival rate of one in four over the course of all four years, as opposed to one in twenty for wizard kids who try to spend their adolescence not in a pocket dimension designed to keep out nasty creepy-crawlies called mals. It's not perfect at it, but it's a lot better than going on your own. If your parents aren't wizards, and you didn't know about magic, your chances were even lower than that, you'd probably have gotten eaten by one in your sleep while you weren't conscious enough to disbelieve it. You'll probably still die in here if you don't have any idea how not to. Wizard hair's a useful magical material, we'll trade you orienting you and a pair of silk slippers for your hair."

"I knew magic was real but my parents don't. Or any of my brothers and sisters. Were the - gross rats - mals -"

"Almost certainly. If a mundane sees a mal and kills it the remains usually end up looking more like a mundane critter than the mal would have when it was alive."

"Oh. Is having - slippers - important -"

"If you go barefoot all the time you'll get bitten by something small and have to cross your fingers that it isn't too venomous. This time. One layer of silk wouldn't be great protection usually, but ours is spider silk, from Darwin's Bark Spiders, it's better than Kevlar." She gestures at the little spider clinging to her neck, a little more than half a centimeter long. 

"So the rat things can't bite through it?"

"It's not proof against everything, you still have to be careful and watch your step, but yeah, it'll keep the little stuff off."

"If magic hair is so good why is practically everybody bald?"

"Because you can only bring so much mass into the Scholomance, and hair isn't a better choice by weight than useful potions or artifices or letters you're being paid to bring to people already inside. You grow it some after induction, but even seniors won't have it long unless they're really powerful, long hair is something a mal can grab onto in a fight. Plus, it's more useful for us than for most artificers, since Wilbur," she nods at her brother, "has an affinity for thread and fiber."

"I like my hair."

"The position you're in really sucks. If you wanna go off and talk to some other people to confirm that we're not just trying to scam you out of it you can do that; you might even get another bid for it that you like better. But you can grow your hair out again after graduation, if you survive, and in the meantime you're going to be without fresh air or real sunlight or anyone you've ever known or the assurance that anyone you meet today will still be alive tomorrow."

"Do you have the slippers right now."

She takes off the slippers she's wearing (she has socks on underneath, which are also spidersilk and therefore almost as good).

Rebecca tries them on to see if they fit.

The fit isn't exactly perfect, but they sort of mold into her feet instead of flopping around where they're too big. 

She takes a few steps in place. "Um. Okay. You can have my hair. I guess."

Wilbur pulls out his thread scissors, and Lucy carefully trims Rebecca's hair off, not all the way to the scalp but very, very short. It at least looks basically on purpose. Then she twists the hair into a hank and hands it to her brother, who puts it in his pocket, and starts explaining things to Rebecca like how you really don't want to sit next to a vent or go to the bathroom by yourself and the cafeteria food can be infested by poison or mals, except the brussels sprouts which for some reason are always safe, and how to store mana. 

"Brussels sprouts? Really?"

"Mum insisted on making sure Wilbur and I got used to them. It's better than it being something popular that they'll already be out of by the time you get there."

"I... guess. So this is a school, right, where are the teachers."

"There aren't teachers. You get taught by the school itself. Schedules appear in front of you when you look away, worksheets go in slots, language classes involve voices from nowhere talking to you in your little soundproof booth." 

"...that's kind of cool."

"It kinda is! The Scholomance is terrible but it's a lot better than the alternative. You said you'd figured out you were magic, any idea what your affinity is?"

"No, what's that? I didn't do a lot really... sang my plants back to life when they were wilting and stuff, mostly... I could always get Judith to go to sleep..."