On the Polynesian islands there is a vampiric demon known as a tü (“war” or “to stand”). When a person wants the power to communicate with the dead, he eats a piece of the corpse belonging to the person he wishes to converse with. The spirit, the tü, that once resided in the body will return and appear to the person, seeking to start a friendship with him. As a show of good faith and wanting to make friends, the tü will offer to do favors for the person, such as attacking those who would do its potential new friend harm and drinking their blood.

Source: Carlyon, Guide to the Gods, 382; Fornander, Account of the Polynesian Race, 170; Handy, Polynesian Religion, 265