Sam and Dean told Bobby to keep an eye on him.

No one really trust Crowley, why? Because he was too intelligent and cunning. The boys went on a hunt and they let Bobby to watch over Crowley.. That wasn't going to end well.. Not because of the wheelchair, no, just because it was them.

Bobby was looking at some books about the apocalypse while Crowley was just wondering around the circle of salt that he couldn't pass. Crowley was definitely bored, and Bobby could tell by the bored sounds that Crowley was douing. In a moment, it got annoying.

-- ' Stop doin' those sounds and stay quiet and pretty. '

Bobby grunted as he continued to search about the apocalypse.