|“|| Sam: You know, I knew you'd come looking for me, after Sioux Falls. I suppose you had to.|
Dean: What you did to them. What you did to Bobby and Jody...
Sam: They tried to stop me. But I will not be stopped.
After Sam became the leader of a demon army after going evil from drinking demon blood, Jody and Bobby Singer attempted to stop him to no avail. In retaliation, Sam killed them. Jody and Bobby's deaths drove Dean to hunt down an unrepentant Sam who killed Dean as well.