Relieved to see Dean, much less the familiar vehicle along with him, Cas climbed inside and closed the door, listening for the familiar creak. He didn't ride in automobiles often and usually, he disliked it. Yet Sam had once explained to him that it was imperative to respect another man's car. It made little sense to him, but he was willing to abide such a rule if that was so. "Hello, Dean," he said softly.
He then spotted the holy water flask in Dean's lap and nodded. "Do you have a silver blade?"
While he knew that Dean often saw him as naive, he knew the ritual by now. Trust was something that could rarely be afforded among hunters and he understood that Dean had no reason to trust him at the moment, especially considering he was all but entirely human. He may have still had his own blade on him, the one forged in Heaven, but it would likely be better for Dean to provide one he knew was safe. If he had to bleed, then he was willing to do so.
Otherwise, he didn't quite know what to say. He didn't wish to disrupt the timeline, yet Chuck had told him it had already been disrupted many times over. Not know how true that was, he waited for Dean to speak first and braced himself for the inevitable splash of holy water to the face.