Castiel was relieved. Although he suspected his Father would have shown disapproval by now had he been concerned about Dean's behaviour it was good to hear in his Father's own voice he was not concerned. One of the things that had been concerning Castiel the most was a tension between his Father and his charge. He knew Dean would come off second-best and he he did not want Dean to be on the receiving end of his Father's wrath, even if it was deserved.
Castiel's eyes strayed to the being sitting at his Father's opposite side. He had paid him little attention, his Grace muffled by their Father's, until he heard his Father use it's name. That was when his eyes went wide, he tensed. For a moment he lost sight of his Father altogether. Only saw his brother. On his face was a look of pure distaste.
"What is he doing here?" Castiel spat. "Why is he walking free?" He did not address Lucifer directly though that would not hold.
He backed away a little, sliding across the pew but his eyes stayed fixed on Lucifer. He had to stop the next words out of his mouth. Now is your chance, Father. That would have been over-stepping his mark but he knew his Father could hear the thought. Castiel didn't know what to make of his brother's presence but he knew he had to keep him from Sam Winchester He knew his Father knew this too but Castiel had found, lately, may things he thought he knew were not even close to true. He had to trust Morningstar was under their Father's control. It was the only thing stopping him tearing out his brother's throat. It was the only thing keeping him from blasphemy.