Contrary to what people might have thought, it wasn't Ruby that Castiel was tuned into, it was Dean. Ruby had begun to prove herself, in that slow, painful way that still twisted at his heart far too much, and now he let her walk around without the constant supervision, instead checking on her every once in a while, even if he did still look through her mind to see everything she did when he wasn't looking.
Tonight it was Dean that Castiel was focused on, wanting to do a better job of protecting the Winchesters and their loved ones than he'd been doing recently. And he felt the gunfire like a kick to his own chest.
It took him only a moment to find where they were, appearing with a flutter of wings. Dean, bleeding far too much, Claire only recently recovered from being hurt again and Ruby, Ruby was there holding out the knife. And around them were the bodies of the dead and the dying, the half breed demons that were the real victims.
Were he human, Castiel would have been holding his breath at the scene before him, standing just a fraction out of their sight as he waited to see what would happen. Dean would not die, he would see to that himself if he had to, his presence making that possible. And now he wanted to see what would happen between Ruby and the Winchesters.