Weirdly enough I have a character sort of like that that was also ****ed up in the head at one point. Her name is Remilia. She starts out ****ed up because no one liked her due to her psychic powers, and went completely bonkers when she couldn't 'see' you. (She merits existence on emotion, and you're blocked from her powers.)
When she's beaten, she tries to get over that, though people still hate her with the exception of the other members of the Elite 4 (And she finds that out just after she's beaten, too, which is probably the reason she doesn't want to kill you after that.) (And the 8th gym leader, but he doesn't hate anyone except one of the Evil Team Admins). By the time she gets kidnapped in the second game, she's not nearly as crazy.
... Though that doesn't mean she doesn't measure existence through her emotion sensing. She tries not to, but... she can't get over it. She is a bit shy when she's out of insano mode, but... it's better then what she was before.
And yes, this was a villain of mine.