Castiel nods, carefully lowering himself onto his knees as he mulls over this not entirely unanticipated news. Feared but not anticipated.

"Dean will want to help keep the city safe in any way he can," he murmurs, chest tightening at even the idea of the threat of anything that can affect Dean so cruelly. "I think you know that I hold back my power much of the time as it is dangerous in such a small place and I have a...difficult history with losing control. However, I want to help as well. I don't want those things getting to Dean or anyone else, again. Come to us both," he finishes, the air vibrating with more of his Grace than he would like.