Who else had red eyes though...Crowley! Wouldn't that be a "hell" of a twist. Because, if Crowley is dead, then he'd be in the empty, right? And he was kinda connected with Cas, so maybe when Cas "woke up" the Empty or messed with or whatever the heck he did, it woke Crowley up as well. Honestly, I'm just looking for a way to bring Crowley back (and not Lucifer!).