Okay, just-

Angel With a Shotgun.

There, I said it. This is the Destiel song and no one can tell me otherwise. I mean, just the lyrics, it's basically Destiel put in a song!

I'm an angel with a shotgun
Fighting 'till the war's done
I don't care if Heaven won't take me back
I'll throw away my faith, babe
Just to keep you safe
Don't you know you're everything I have

Like, how is this not Cas signing?