The first thing I'm looking for a fic which if i remember correctly was a one shot. I'm pretty sure it was a Destiel fic, but i don't think they were in a relationship as of yet. Anyway, in the fic Sam and Dean had to drown Castiel so he could crossover or... something. It all went down in a barn and Dean had a bit of a freak out i think because they had to hold Cas down under the water while he was thrashing. 

I know that isn't much to go on but if anyone can find it, or something similar even, i'd be so grateful :)