When we talk about Hellboy (2004), those elements come into play. The basic plot is simple: Nazis trying to touch the occult summon a demon who is raised by the good guys and turns good himself. He fights various "things that go bump in the night" because he is equipped to handle them. Eventually, however, the people guiding the Nazis will return to bring forth the Apocalypse at which time Hellboy (Ron Perlman) will have to choose; is he a man or a demon?
But of course there is the subplot surrounding the relationship of Hellboy with Liz Sherman (Selma Blair). It is obvious the two of them
It is obvious the two of them share a past together. Her firestarting abilities would be troubling for most people but for Hellboy...well, a running gag is "fire doesn't hurt me!"
He inquires of Abe Sapien (Doug Jones...who sounds a LOT like David Hyde Pierce whom you remember as Niles Crane on Frasier) on how to slay Sammael. Later Abe is injured and taken out of the equation...but I suspect he will have a larger role in the upcoming sequel.