the undead hunter. I have entreated the swift sword, to strike, that I at once be freed
With vampires living in secret among humans and other beings alike worldwide, each oldest and ancient royal families act as overseers over their own covens and their bloodlines for decades to come while hiding and concealing their own rare forms of disease that left them to consume blood of all living beings to survive, it is more of an rarity if there was such a creature, an half-breed of both vampire and human who can survive without the desperation and the urgency to depend on blood for survival.
Much of Wren's backstory remained an mystery as he rather remained in the shadows away from the public eye, but it can be speculated that he was one of the family members of the secretive royal family of vampires with an exception he came out an half-breed rather than pure-blooded. But instead of perhaps allowing himself to be fully turned to vampirism to carry on his grandmother's legacy by taking the throne he turned to hunting down other rogue creatures of the night - ones who instead hide in the shadows and keep peace with humans, prefer terrorizing and killing others.
For decades he became somewhat an ghost story for the vampires outside of his royal family's circles, no one really knew who he was or what his motivation was for deciding to risk exposing himself to protect other humans by becoming an monster hunter but for him it was rather something he would rather do is keep his past to himself and protect others from dangerous rogues that he would likely make enemies out of in the long run.
Now as an private detective, he takes full advantage of his seemingly "mundane" occupation to investigate unsolved and strange cases which gives an chance to continue hunting the rogue supernatural creatures or even assist others if needed.