Blaumro

Blamuro was once a vampire hunter, but was later tortured into becoming the guardian ghost of Boris Tepes Dracula

About
Blamuro is a vampire hunter who hunted Boris' ancestors 500 years ago, believing them to be, as ancestors of the Count Dracula, to also be vampires. However, eventually they had enough, and the family succeeded in capturing him. They then tortured him until his sense of right and wrong was completely destroyed, and in turn also eradicating his personality, before killing him to serve as a Spirit Ally to the family, who had learned to use shamanic abillities to become vampires.

History
500 years ago was the descendens of Vlad Tepes still beeing hunted believing they were vampires. One of theese hunters was Blamuro. However during this time Hao came and taught the family how to become real vampires by using Shamanic abillities. The family succeeded in capturing Blamuro and kept torturing him until his sences was completly broken and there was nothing left of his spirit but a humble servant. It was then he was killed and became the guardian ghost of the family. 500 years later the child Hao sough out the 22 year old Boris Tepes, the now living descendent of the Tepes family and the inheritor of Blamuro, who instantly swore him loyalty.

Anime/Manga Difference
In the anime, instead of beeing a spirit from 500 years ago, Blamuro is a now-living person who alongside others hunted the last decendents of the Tepes Family, being Boris and his parents. Boris was able to escape, however Blamuro succeeded in staking his parrents who did not turn to dust, like a vampire should. It is then that he realizes that they were humans and started to search out Boris.

However when he finally finds him, the now adult Boris, is together with the child Hao, and Blamuro is stabbed. Also in the anime he serves Boris as a way to atone for his sins of killing humans.