NO_PHYS_ATT_GAIN - I noticed this tag in a couple of the entries in the new interaction based nightcreatures. Does it prevent future Attribute gains for the creature?
It certainly sounds like it does that. It does seem a bit weird that necromancers and vampires would have that tag, but the presence of that tag could be randomized.
Yeah, it locks attributes in place. For some reason, I didn't imagine vampires being able to lift weights and load themselves out. I dunno if that'll be randomized in the future. As a general note, you can zero out the number of random vampires and use the example vampire to make your own work how you want. I'm not sure when we're going to have parameters for how the randomization actually works. I think the current plan was to do that first with random dragons, but I'm not sure what the format is going to be.
In almost every interpretation of vampires in every mythology, vampires gain power over time. The older a vampire is, the more powerful it is - including being stronger and faster. The more blood a vampire drinks, the more powerful a vampire is.
Why did you decide to abandon this fundamental aspect of vampire lore? It has nothing to do with working out, granted, but vampires being stuck at particular attribute levels for all time is absolutely bizarre.
Citation needed; I don't think it's even that common, and certainly not the general case. In particularly, it sounds like you're talking about vampire *fiction*, not vampire *mythology*. Remember, DF is set generally pre-1400; and my impression is that the sort of tale you're talking about is generally Victorian or more recent. I'm doubtful you can come up with references that even a majority of, let alone "almost every" example of, of pre-1400 myths about vampires work that way.
In the most general terms, tales of vampires were originally about the horrors of *death* (and death gone wrong), with a lesser component of being about disease (particularly plagues). Then the Victorians (in general) with their particular world view picked up an old set of tropes and rebuilt them as being about the horrors of *romance* (and romance gone wrong), with a lesser component of being about disease (particularly sexually-transmitted diseases). Then modern writers have picked up the tropes again, and rebuilt them again as what amount to fetish fantasy, with the "disagreement" between types having at the core what (set of) fetish(es) the authors are implicitly or explicitly using their vampires to represent / explore (bondage, ageplay, bloodplay, consequence-free satyrism / nymphomania, and so on).
From a more specifically DF standpoint, my take would be that
IF (some) vampires can gain additional power from blood (as opposed to a more traditional take where it merely slows their decline), that should be a "magical" interaction, and probably handled by the same sort of framework that would be needed for an adventurer to gain strange magical powers from the blood of a powerful beast (e.g. spear-resistant skin, the ability to understand the language of birds, or other mythological standards). Said interactions would presumably override ordinary limitations by their magical nature. The currently implemented tags prevent a vampire assigned as, say, a miner or pump operator or other task that can buff physical stats from getting more ripped due to their job, which IMO is as it should be.
A related question is how vampires and necromancers interact with the skill decay system; if there's not some care taken, they could end up as ageless incompetents.
Toady, do vampires, necromancers, mummies, and other "atypically old" variant creatures have any special handling for skill decay? It seems like that agelessness should provide at least some protection, otherwise they may end up as unusually incompetent in old worlds.