One origin I’d been toying with might be useful to you.

Simply put, the Stryx’s natural state is one of pure stasis. In their natural habitat, or what was their natural habitat, time simply does/did not exist. Kindred pseudo-immortality is an inherited trait from them. For whatever reason (the fall of Pangea or Atlantis, intervention by the God-Machine, pure curiosity, whatever) they deemed it necessary to enter the Prime Reality of the WoD. Kindred were created possibly larval forms of the Stryx, or necessary chimeric man/monster organisms whose spiritual resonances allowed...