Tsukuyomi: Moon Phase2004

Elfriede:
Human blood is how we vampires sustain our own powers. Immortal blood, the blood of other vampires, is how we obtain new ones.

Kouhei Morioka:
Whadda you mean?

Elfriede:
You see, power, like my ability to summon how the count used to manipulate light, can be absorbed by any other vampire if he drinks our blood; so, if one of us desires a new power, we have only to find another vampire who has it. Of course, few vampires will share their powers willingly.