It's difficult for human writers to write the psychology of immortal man-eating monsters that don't exist in reality.
It's not that difficult if you keep in mind the tenet of being a vampire in the 1st Edition: you're losing humanity as time goes on, the only difference is how fast you do it. So you are:
1) Becoming emotionally detached/dead, because it is not possible for a vampire to forge a lasting connection with humans as they inevitably die.
2) Start using others more and more instrumentally, even if it's just a force of habit and something you need to do merely to ensure your own survival.
3) You develop severely trust issues as the people you interact with are the other vampires, who might be using you (at best) or trying to kill you (at worst).
4) There is a strong desire to give in to your Inner Beast as well as your addiction to blood that can overrule you (which, I feel, isn't portrayed as well as it could be in various media. I think Vampyr was going in the right direction, from the little that I have seen of it).
What you can fiddle with here is - as I said at the start - the degree of all of the above, as well as the individual interests of particular vampires.