"The fire is enough right now, idiot," Lucifer tsks, though not unkindly, before the rest of it catches up through his mind and the first lock-up of Lucifer's thoughts follows, though not stifled entirely. Just like how Lucifer can physically tense oftentimes. Outwardly he looks as though nothing had changed. Don't get involved with it, Istredd, it comes across sharply in warning. Anything else, fine. But not that.

And any thoughts around the why of it are obfuscated, if only because knowing will make Istredd more willing to get involved. But Dean with that blade could gut through Lucifer into the heart of his celestial being.

And he will shred through Istredd before he even tried a spell.

Lucifer refuses to allow that any chance of happening.