How do teegee, how do.
Specifically, I've already played the region that the campaign will take place in as a dark corner of magic in an otherwise increasingly enlightened world, with a strong history of vampires. I'm just stuck on justifying such a wide variety of monsters working together, or at least living in close proximity, and worried about how big the various castles will be, as to whether the players will get sick and fucking tired of 10-15 sessions taking place in the same huge-ass castle.