Neil means it. He's sure, and for once, Dean doesn't dismiss him for an amateur in all this. He's seen too much, is still bearing the scars of too much, and maybe he doesn't know all the whys and hows but Neil's not backing down, and he's got Sam and Cas and Mike to stand with.

Somehow, it makes it easier to hold the demon down a moment longer, raise his gaze past his own blood splattered boots and find Neil's own. "You're a good friend. Sorry I never told you that."