Kate, your roommate, is a fairly ordinary person. She follows a basic routine: wake up, commit vigilantism, stay up at ungodly hours, eat, repeat. It's only when you take a closer look at her routine that she begins to seem a little odd.

Perhaps vigilantism isn't exactly a normal thing to do, but considering Kate is not the only person in the world who fights crime while parading around as a bat, you choose to think it's at least normalized. Still weird though. Staying up at ungodly hours? Sure, it could just be a bad habit, but you're pretty sure you've never seen her sleep. Ever. As for consumption, she doesn't necessarily eat. She just puts food in her mouth and swallows it whole like a vacuum if she's feeling goofy. Primarily, she feeds off people's blood (at least, that's what she tells you).

And now that you think about it, you're pretty sure your roommate is a vampire. But she's still mostly normal if you decide to ignore the vampirism.