[He shakes his head, eyes closed. There's a flash of pain across his face — it is not from Lucifer, but of raw emotion from terrible, terrible memories. Memories of after he said yes, but — also memories of before.]

To be honest, I really, um. I don't have much left to spare.

... It was bad, Cas. The years after I last saw you and Dean, it — [He sighs, shakes off the worst of it. Selfishly languishing in his misery, in his mistakes and punishments. It's stupid. It doesn't matter; those days can sit with him, only him, as they rightly should.] It doesn't matter now.

What matters is... trying to do something with this... small opportunity I've got.

For whatever its worth.