Recurring antagonist Options

[Raiden]

So, I was thinking about have a psychotic delusional vampire genius as a recurring "villain" for the PCs, would be a mystic adept and be much stronger (at least karma wise) than a single PC due to well, living long enough as a vampire to go insane (and still think your quite sane). also thought about him having MPD, with one being the insane Doctor/scientist and the other being a more civil, polite, and charming man. I plan to have him "catch" the PCs at one point not sure how to do this without railroading or seem as if I am going on a DM power trip, any tips on that as well would be nice. anyway after catching them the insane doctor would preform experiments and the like. some actually ending up slightly beneficial, some detrimental to PC health but most just puttering out in the end with no real effect. after a time the PCs would somehow manage to escape (not sure how to do this either) and yadadada so on and so forth. now this was a one the spot, lightbulb that I started to run with. any thoughts? ideas? ( its a horroresque game so, terrify me) oh, also the guy is hell bent on causing a new pandemic of the ghoul strain and then using a spell he (and his mentor spirit made specifically for ghouls) to control all or most life left on earth. :3 (of course we all know the best he could do was take over say, the UCAS or some around that hehe) I think I would have the PCs start working for him a run or two getting him things he needs without knowing it. sorry I am rambling as I think. anyways thoughts, ideas, the works :3 thanks guys.