There's this book series that I only remember the gist of and one scene in particular that stood out to me. The scene is in an elevator with the main character and his friend and a beast, maybe a werewolf, attacks them in the elevator. He knocked the friend out and proceeded to choke the MC who had a special knife that he was going to stab the creature with, but ended up cutting himself with instead and poisoning himself. Anyway, the creature gets away and the MC almost dies. The possible werewolf has a master that may or may not be a vampire. I know the end shows the MC in a cave trying to find and kill the bad guy and there's a girl involved I think. The MC may be a vampire or half-vampire and there's a scene I vaguely remember with him fighting police. I just barely remember these books, but I just have to find them. I'm not sure if I read them on here or not.