I suppose that as with some humans mental illness is entirely chemically based - as in, the brain chemistry is off in some way, it could be the case with him, too.

One woman I know was a paranoid schizophrenic, and for a time, they were able to find a medication that balanced out certain brain chemistry and she was fine, but if she missed a dose, it was all over because then the paranoia would kick in and she'd see the medication as a plot to "get" her. It was sad, but just something about how her own brain chemistry. I hope the Prozac helps Runt. I wouldn't call his behavior Bi-polar, though, it seems much more random than that. Are there any indicators of when he's about to "go off?"