OP, just because your cat is affectionate and gentle with you doesn’t mean it’s going to be that way with a stranger…. I agree that it’s very possible that your roommate did something to get your cat aggitated, but it’s not the only possible explanation. With cats, they usually shy away from a stranger who wants to pet them, and pushing that can bring out aggressive.

Sometimes cats are just like that....1 moment they'll be puring and loving a good scratch/pet the next they'll just flip and go for claws to the face.

Set up some cameras.

OP here. Now that I'm not restricted by the character limit. He LOVES strangers. Strangers are best friends he's never met. He begs the maintenance guys for my apartment for pets. He cuddles and gives face rubs to the vet. He ****** himself out against the walls of the catio when neighbors walk by. My best friend picks him up improperly every day. That's why it was so weird and alarming to me that he scratched her. He goes to the vet tomorrow to make sure there's no underlying issue, and my roommate and I need to have a talk about how much she actually knows about how to handle them. She claimed she was a huge cat lover before she moved in, but I have since realized that doesn't mean she knows what she's doing. I posted the same story on reddit and they lowkey set me straight in reminding me that he is, in fact, a cat, but it's still wildly out of character for him. I hope a reconciliation can happen, because if it can't be and it gets to the point that someone needs to be rehomed, I have bad news for my roommate.