I always wanted to see a playable vampire in this game, slay some rats and northlanders, “secure the cattle”, as we used to say in Sylvania back in day. I had hope to see him (or her) as a separate hero, but as Fatshark mentioned - they have no plans for the new heroes. This is why I suggest Victor, as a hero, who can become vampire more likely than others. Elves and dwarfs, due to lore, are bad candidates for becomming undead creatures of the night. Kruber is already Grail Knight, and Sienna does not really fit into classic vampire gameplay as most people see it. As some already might know, blood kiss transforms not only body, but the very mind of the victim, so he will partly loose his former personality. This can cause some problems with his battle comrades, but during the End Times vampires had fought on the side of the Order. Vlad von Carstein was restored in his rights as an Elector Count of Sylvania and helped in a battle with chaos hordes. This is why, I think, in this particular circumstances, Ubershreik four can tolerate vampire, specially when taking in consideration of who he was. Also, we had vampire in lore, who had their dark nature under controll, and served the righteous cause - Jerek von Carstein. This can justify vampire in our ratslaying team. Also, vampires of von Carstein bloodline can walk under the sun, so the weather - not a problem.
What I suggest for mechanics: there can be several ways to represent vampire, as giving him buffs for drinking blood, decreasing health for not killing enemies and so on. I’m not sure about creating new feeding mechanic, but it will be nice to see some sweet animations, allowing ou not only feast on filthy ratman and northlanders, but also drink some tasty blood from a human beings (your party members). Ult can be either a spell from Lore of Vampires, or Beast Form, that will incease power, attack speed and protection, but Victor will suffer from bloodloss if not constantly killing things or drinking blood. Not sure about ranged weapons, but it can be a unique signet ring with a glove, that will allow him to fire projectiles, infused with dark magic, like Gaze of Nagash spell. Melee weapon - probably haudegen. This sword fits pretty well to vampire. Would love to see your ideas. Let’s inspire Fatshark to make this dream live. Victor von Carstein must arise to show undeath to petty chaos worshipers.
P.S.: Sorry for my bad Reikspiel.