Psst, got a question for ya(completely unrelated to what I'm writing, I assure you). Which members of The Thieves Guild do you believe could be intimidated/cajolled/persuaded into following a(to them) frightening, strict, powerful, (he's just being a bit of a cunt) vampire? (Except Frey. His death is an unchanging point in the timeline.)
To be honest your best bet would probably be Sapphire but you would have to do at least something to get her to feel indebted to you and if possible help her with her trauma. This could honestly help with the vampire bloodlust as well as long as you can again get her to feel indeted to him. Next up would probably be Ravyn Imyan and all you would really need to do is help him find some of his old crew then proceed to help find the rest while fending/killing off the brotherhood.