"I believe so." He had gotten something, all right, but he didn't know what to truly make of it. Even as she vomited the contents of the pie onto the floor he hasn't even flinched at the sight, other than holding onto her shoulder momentarily as if to steady her. As if to prove to her that even then, after the sacrifice she had eaten in order to seek for an answer, she could trust him to be clearheaded enough to not let her fall.
It was hard to be clearheaded, though, when her words raised so many more questions. The Leviathans had weakness. The moon needed the wolf, and the death needed the slayer.
Death. Castiel suffered from not always being able to differentiate between literal meanings, or figurative ones, and he caught himself frowning slightly as he pieced everything together. Destiny had already told him that nothing was ever clear, he knew that well enough by now, but it didn't stop him from asking as he stood up and put on the belt again. "You mentioned death. Do you recall whose?"
He had to ask. Castiel already knew who he would approach with this information, and he just needed one more answer before he could transmit the message to her.