Astrid

Ran away from home aged 16 because her home life was a mess: A fellow student had caught her and her girlfriend kissing behind the tool shed and they were both being bullied horribly for that. Then the girlfriend never showed up at school again. Astrid's dad actually didn't care that his daughter was a lesbian, but he was also distant, deeply absorbed in his work, generally kinda bad at parenting, and absolutely and completely unhelpful. Her mom had been dead for ages. And so, with nobody to turn to, she simply packed a bag and left.

Gus caught her trying to pick his pockets a few weeks later and managed to get her to tell him the whole sad story and he decided that he had to do something, out of queer-kid-with-shit-parents solidarity if nothing else. So he got her a place to stay and a new school, made sure she stayed IN school, then coaxed her into going to university and then got her the Scientific Advisor job at the MASCIU. Not due to shameless nepotism, mind you, but because he'd noticed her incredible intelligence and her somewhat dubious grasp on ethics and her absolutely amazing talent for understanding magical bullshit, and he knew that she'd either end up working for MASCIU or against them... and he was pretty fucking scared of what she might do on the wrong side of the law.

Astrid was not initially fond of Gus and pretty much figured he was just a wimpy fop with few redeeming qualities. She still tends to be pretty acerbic towards the poor guy - mostly because he saw her at her worst and she absolutely cannot deal with that - but she's also immensely protective of him, and hurting her vampire is a pretty good way to draw her considerable anger.

Was involved in an unfortunate but mundane traffic accident fifteen years ago that fucked up her left leg; she usually walks with a cane these days.