What about "civilised" vampires? The ones that want to blend in the community? I myself seen quite often them fiercely defending my fortresses, becoming the heroes of dwarfkind, (apart from occasionaly turning my dorfs into raisins) . Maybe there should be a way to allow them to drink only extracted blood, or blood of cats or something like that. Of course there will be outlawed vampires that doesnt comply but only as part of the vampire community.
i have a different beef than arkhometha, but hold it with a similar stubborn certainty that i am right. i think vampires are defined as bloodsuckers,
and as creatures of evil. a non-evil vampire is a crappy vampire. vampires may even be nice people and be trying really hard, but their condition and powers are unvariably a curse. so while i don't care that a vampire can survive indefinitely without blood if he is locked under a mountain, i don't think drinking blood of a goat, or blood extracted non-lethaly, should do anything for them. drinking blood isn't feeding, it is a ritual, it is the act of committing evil that drives them and not the peculiar configuration of their digestive system.
so you can have your nice do-gooder vampire trying to live in harmony in dwarven society, joining the militia and doing heroic deeds for the fortress, and trying really hard not to hurt anybody, even fooling himself into thinking that he can satisfy his cravings on goblin prisoner blood. The cravings don't go away and the blood has no taste, maybe the blood of dwarven criminals... But going too long without wetting his fangs on the blood of innocents drives the vampire crazy, and one day the local tanner walks home from work to find his wife and children suck dry, their skin like wrinkled paper, their last screams of terror frozen on the expression of their faces, and hunched over his wife's corpse... the hero of the fortress.
The tanner runs out, shouting for the guards. The vampire, shocked by his own actions and released from the cravings that drove them, doesn't give chase, and offers no resistance to the arresting officers. Later that day, the vampire is released. He finds out the overseer has executed the tanner for having murdered his own wife and children.
On his own chambers, the vampire finds a young dwarven maiden, gagged and chained to the wall...