I do wonder what happens once all your dwarves are composed of vampires. Do they just stay active but forever hungry? Can vampires starve themselves to death?
Oh, man... I had my first Necromancer siege. At first, there were only a couple of zombies on the map and no necromancer in sight, no problem I thought, everyone was conscripted and sent out to... meet their doom. Three survivors locked themselves below and trained for a whole year for a breakout. Then migrants arrived and again they tried to beat back the undead. This time only two survivors, all the starting seven were dead.
I first became suspicious when one of these dwarves ("very weak") killed a zombie dwarf rather quickly with no notes on the combat log. Then, I accidentally left a door unlocked and in came the hordes who proceeded to... do nothing. The ghosts, the skeletons, the zombies, all just stood around one of the dwarves. Checked her relationships and it turns out her deity made her a vampire a few years before emigrating to my fort.
Right. I shifted all noble positions to the other dwarf, a farmer, and accused the vampire of murdering a child (which I guess she must have done). I felt guilty about sending the farmer to certain death but, you know, justice had to be upheld even at the expense of the fort. Except he does nothing. Check his relationships and he's a freaking vampire too.
So that's it... I have a fort that consists of two necromancer vampires that could be, for all I know, utterly invincible and opposed to any and all intruders to the map, migrants included. Actually, that sounds like fortress heaven to me... perhaps this is my dream fort? What should I do? Conscript immigrants to restore justice? Or make a vampiric tower that would put Castlevania to shame?
edit - the invincible thing is looking quite probable now. One of the vampiric lady dwarves got a major injury, don't know how, maybe sparring, after I left the game on overnight (a dwarven caravan got massacred so the two of them have a LOT to haul)... chest cut open with a fractured lung. I scrambled to get the other vampire as chief medical dwarf, but before she could do anything, injured vampire is up and about and hauling again. A season later she just has a "dent" in her chest. This is like a dream super-dwarf fortress.