Colin: "You're far too trusting, do you have any idea how easily I could kill you?"
Mark: "Of course dear, you tell me as much, quite often. I'm well aware of how dangerous you are."
Colin: ".....Then why stay? Why show such vulnerability, knowing what you know?"
Mark: "Because no one has ever treated me with as much tenderness and respect as you do, and because I know you'll never intentionally harm me. Whether you like it or not, I trust you."