Ah, but two vampires could be very different from one-another.  Also, that reminds me: vampires make an amusing potential enemy for a regenerator.  Their goal is simple: capture such a person and keep them somewhere where they can be used as a reliable blood source.  

The challenge with an alien mindset is, well, writing a mindset that's believably "alien" when we're not.  Doesn't make it impossible, of course, because it's not like one needs lived experience to write or roleplay something.  Not sure if I have many thoughts on the mindset, though I can think about how that'd potentially work out.  Though the other sticking point i can see there is if blending in is part of the point, can't be too "stranger in a strange land" either.  Gotta break the prime directive sometimes, but can't just do it all the time, either.  It does lead to an obvious limitation to the character as some sort of "technology protection" system that cuts in and puts a time or output limit on their stuff.  

The thoughts I had so far for things are more the big picture stuff, and that's going sort of the way of the Zentraedi from Macross.  Advanced precursor race creates peacekeeping/military force.  Though, probably more machine intelligence, as I do like that angle.  They outlived their creators (didn't go all Skynet and kill them, at least) and are more or less continuing in their original role, just also trying to figure out a place in the universe without their masters, and with plenty of other stuff.  

The general feel I'd be going for is sort of Green Lantern space cops or the like, just as an autonomous system that's going "well, we still have all our orders to be space cops, now what?"  Or...something like that.  

And to cap off with more brainstorming on powers to play with, whatever origins the character has, something like manipulating force fields for defense (and attack) might be fun.  I'll figure something out, but it might take a while.