"The future…" Crowley whispered; his eyes were focused on the nightscape beyond the side window. London was still a fair way off, however, the almost-apocalypse seemed even farther away now.
"Did you say something, dear?" Aziraphale asked.
"Fuck ineffability. The future is not inevitable." He squeezed Aziraphale's hand and left no room for doubt. I will protect you — an unspoken promise — I will protect both of us.
"The future is down to you, down to me."
They averted the apocalypse, thwarted the Great Plan, faced Satan and lived to tell the tale. Whatever their former sides were going to throw at them, Crowley would be blessed if they as much as lay a finger on Aziraphale. Or himself, for that matter.
"Yes." Crowley could hearthe angel smiling. "Yes, my dear. You are right." Aziraphale leaned on him and breathed a sigh of relief.
"The future is down to us."