I like this a lot. I like the ending scene, and parting-for-your-own-good (especially when the other party wouldn't let them if they'd known) is something of a kink of mine, and I like the way that it's both in the past and not, and this is the first fic I've read that really convinced me that McKay/Weir could have worked at some point in time, even if not during the period when I watch their interaction.

Actually, this or something very like it is probably going to go into my mental backstory for the two of them now.