I believe it was either a Forgotten Realms novel or a Ravenloft novel about a surface elf (I believe his name started with a J), that was turned into a vampire. This referenced the part about growing things withering at the touch of a vampiric elf. I never really got into Ravenloft, other than playing, the SSI Ravenloft RPG, where if I remember correctly Drizzt showed up as a joinable NPC. I always found the Ravenloft setting too creepy, less so than the Call of Cthulu rolepalying game, but creepy nonetheless. I'm not afraid of the dark, just what might be in it
I like option 1 better myself. Instant is evil hard to fathom. But then we (based on input from our limited senses and societal paradigms) don't live in a world were magic is the rule and demons and devils are but a plane away.
One of my favorite villians (those guys you love to hate) is Baron Vladimir Harkonnen of Dune fame. Greedy, corpulent, conniving, devious, amoral, and ruthless. His physical grossness and personal habits in my mind showed the world the evil behind his feingned facade of being a gentlemen with a legitimate vendetta. Then Kevin J. Anderson and Frank Herbert's son explained his physical appearance as being caused by something outside his control, which for me reduced some of the evil I felt him to represent. I liked him better as a villian when it appeared that he was disgusting because it suited him (Choosing to be evil) to be that way rather then when it was forced on him (Instant Evil).
I imagine being cast dominated and humilitated for years can lead to quite a bit of pent up rage. I wouldn't expect it dissipate over a shared sunrise.
Jack the Ripper was most likely insane. I know some of the D&D references having mentioned Chaotic Neutral as the aligment most often associated with insane people. But it never really states that everyone who is Chaotic Neutral is insane. Definitions for insanity definitely have their their fundamental basis in societal values. In that regard, I would consider a vampire insane and thus find it plausible that they would be capable of instant evil, well, what I consider evil, meaning attacking me for my bodily fluids.
Still, no one wants to see the hero succumb to evil especially after seeminly walking from having a life time of it inflicted upon them. Best to keep in mind that, some of the greatest heroes have been the greatest butchers, it all depends on if you were on the heroes side or the butchered side.
After restoring Solaufein from his vampiric power trip. It really does beg the question, "Were you on the heroes side or the butchered side?" Continuing a romance with Solaufein most likely depends on your personal answer to that question.
Cirerrek