Miles slows a bit. His younger self may be able to read him too well ... but Miles can read himself right back.

"All right. I swear it. My word as -- " He hesitates, uncertain. "-- Myself. Whoever that is."

And that's the truest oath he can make right now. But it's not the end of his other self's story, he thinks. He looks his other self up and down for a moment. "Who are you going back to?"