[Bruno]

The traditional eastern-european Christian interpretation of the Vampire is that a vampire is a dead body posessed by a demonic spirit. Like a posessed living body, the posessed dead bodies know everything the original person does, but are animated by a completely "unnatural" or unholy force, instead of by the original soul.

In a fantasy game, it doesn't necessarily have to be a demon animating the body of course, any sort of spirit, elemental, ghost, or even a magical or psionic energy pattern/program/whatever.

This is a very handy concept for the fantasy GM, especially one looking for the traditional "Undead are monsters, or at least dubious NPCs, and not PC fodder" approach.

I don't see a problem reconciling the ability to access the corpses memories despite the soul being gone - memories are physical structures in the brain, which depending on the setting may be "backed up" or "mirrored" or "echoed" in the soul, the akhashik record/racemind, or whatever, or may not. In a setting with physical memory storage, you just make a footnote that part of any mind-transfer magic/psionics/whatever includes "updating the psychic memory backup" before transferring the minds, and depending on the method used, the transferred mind may NOT automatically get the "decryption keys" necessary to access the stored copies found in the new brain.