Okay, so this is beyond awesome, as is @alternativetodiscourse‘s Rabbi.
If, in order to avoid looking like they might be doing a forbidden thing, the vampire has to wear a cloak and go bleh a lot, does this the imply that the Jewish vampire would be forbidden to conceal the fact that they’re a vampire? Seems like that could cause them some serious issues since modern stories involving intelligent undead nearly always assume you have to conceal what you are in order to survive. Which I guess might be permitted if the vampire counts as alive because you have to preserve life?
On the opposite assumptions (that is, if vampires count as dead) I knew someone who I think is ethnically Jewish but not practising IRL, who played a (formerly) Jewish vampire in a live role-playing game. The vampire’s assumption (and that of the setting) was vampires=dead, and so she didn’t consider herself a Jewish person any more really because that’s something for living people but the way she saw things was flavoured by her having been Jewish in life - in particular, because she was a walking corpse she was always ritually unclean. So, her way of holding on to her traditions was mostly to avoid what most of us Gentiles might think of as ‘Jewish stuff’ - that is, most forms of religious worship and celebration - because she respected those things too much to do them wrong by trying to do them while impure.
The interesting thing was that it ended up almost perfectly replicating the vampire-repelled-by-religious-stuff trope, but instead of being supernaturally repelled she just wouldn’t touch a holy text or go near a temple because she was respecting purity traditions as she understood them. Where at all possible, she avoided even touching living people because of the impurity thing.
Anyway I don’t remember this very well nor do I know enough about the relevant traditions to explore this in more detail but I do find all of this fascinating both as a writer of stuff with vampires and just generally.