No pun intended - whenever I hear the Killer ... I always think of John Woos classic movie. A movie that really changed a lot for me - and I suspect not just for me. I like movies from everywhere and try to watch as many as possible (which you may have already figured out) ... but Killer and Hard Boiled were quite the revelations for me.
Now this has nothing to do with that movie and stands on his own. Like the titular character. He knows what he is doing ... and he still will do anything his girlfriend tells him to do ... even babysitting. Which is not an easy thing to do anyway - but even worse when the subject is attracting evil people ... and trouble. I would not entirely blame her - spoiled as she might be. But it also helps the story move along ... and gives us a lot of action sequences ... very well choreographed ones at that.
The stoic nature of our main character, the knowledge that he is better than others ... well maybe you can identify with that - like I do. I'm just kidding of course ... we wish. Great action cinema ... paper thin story, but enough to keep it all moving along. With a main bad guy, we get to see fight our guy over and over again ... what more could you wish for?