Foster is a werebear who used to rely on the Sanctuary after being disowned by his Mage parents for turning into a nasty hairy animal. He and his sister Amethyst are out on their own now, but still visits sometimes. He remains connected to the mages largely through the unwanted attention of Jonathan Strange, who keeps checking in on him and reporting back to his dad??? Fuck off, Strange.

He's also a Warlock, which made picking which of these to reply to kind of hard. He's made a pact with a Demon (the Psionic) and his powers include magical gaslighting (single-target memory erasure, aka, I totally didn't do this thing, what are you talking about) and the conjuration and control of fire at-will. Tragically for everyone, he can also do these while in the form of a several hundred pound bear.

He and Amethyst live in the same apartment building as Lapis Lazuli, with whom he shares a wall.

I have probably over-used the bold here, but oh well.