I like the adventures of Dean and Castiel. The acting performance that Misha Collins gives as the rebel angel makes the trouble that Dean drags him into so much fun to watch. I think they are going to have a good time together, but it will come to an end. Dean will probably realize that Castiel is an angel without human emotions. Castiel will be amusing for a while, but ultimately I think he is a purpose driven killing machine with no true regard for human life. I think Dean will want to join up with Sam again after he realizes he misses him. Sam's flaws are what makes him human and they are bound by their experiences together and blood. Because of this, I predict that Dean and Castiel will have a falling out or Castiel will be killed.