Sounds like a vampire, or similar to.

Anyone else play Skyrim, and only use Serana [Dawnguard DLC] as their only follower?
Serana: Essentially a vampire princess who wants her dad [who wants to destroy the sun] dead. Like, the only follower that has an independent personality with conversations that have some semblance of a person.

HEEEYY
Ellri!
Wanna team up[ish]?
An apprentice Blademaster who loves stories and myths and books, teamed up with a semi-sane vampire fledgeling [or something]?