Now you are more than likely asking yourself, what is Castiel's cutie mark?! I want to see his cutie mark! But there is a specific reason I drew him like this, me and my friend Amanda both agreed that we don't think Castiel has a cutie mark. He's an angel, not mortal! Only mortal ponies have cutie marks. I think if this crossover were an actual thing, one of the reasons that Castiel wears his coat is so that he can hide the fact he doesn't have one so he can try and fit in. If he wanted to have a cutie mark, he'd have to choose one of his own, and I don't think Castiel would know what to pick. Think about it a bit.
The next thing your asking yourself, is am I going to start working on requests any time soon. Yeah, I am. But I have been pretty art-phased into working on this set. When I do get inspiration, I really want to get it out while I can. Im really trying to work on these characters so that they are easily recognizable for their character they were designed after. Specially with the expression, I really hope I am getting these expressions right.