I work on a strict policy - if they're a threat, waste them. Francis was the one to kill for me, he knew about Niko's past and the sonofabitch even blackmailed him with it. Derrick was just a smackhead, but atleast I got paid for my work with him.
Dude, the f*cking title of this thread is a huge spoiler by itself. I now know that later in the game i will have to kill either Francis or Derrick, which is f*cked up since i'm only 50% through the game.
Use better titles next time. "Question about Francis" or something would have been better.