Vampire is a status unique to the boss Drake. Any damage that would cause a character inflicted with Vampire to be killed instead leaves them with 1 health, with the exception of fatal attacks from the Wooden Stake and, interestingly enough, any attack from Bear Maul.
In the Parallel Universe episodes, Vampire is changed to Vampire?. This status instead restores all health to the character with Vampire? once all health is removed once. Afterwards, the Vampire? status effect is removed.
The Wooden Stake? offered before the parallel universe Drake fight does not remove the Vampire? status effect.
Excess damage done before the Vampire? status effect is removed does not carry over when Drake revives to full health.