She didn't just think she was a witch, which I was mostly OK with because religions are weird and stuff, so I thought as long as it doesn't reach the realm of life-affecting problems, it's a non-issue.
She also believed she had friends who were werewolves, she could do magic, the date of your birth determined your personality, because a planet was in retrograde good things were about to happen, vampires started the Red Cross so they could always have access to blood, and, oh yeah, along with her two mortal parents she also had an incubus second father and that she was half-demon and that's why she liked sex when she wasn't supposed to.
That... That girl needed some serious help, but claimed that she was well-adjusted and fit to help other people instead. Because, of course, she was also an empath...
Edit: I want to make something clear that it suddenly struck me I haven't; with all this craziness that she believed, that young woman had her life a hell of a lot more together than I did or do. She graduated university while I flunked out, she found a job while I'm being rejected every time that I apply, she found a low-rent apartment to live in while I'm still living with my folks. Don't get me wrong, girl had some trauma and had some problems. But she was contributing to society while I'm fucking around on the internet because I can't seem to make anything of myself.
Started out as co-workers in a university work-study job, had a short relationship.