My favorite moment from SGA 5x02 The Seed
...besides John being violated by a tentacle, I mean.
KELLER: Colonel, when you were in the future and you learned all those things that were going to happen [ed. note: she is referring to the timeline where John disappears and Rodney marries Keller but then she dies and Rodney spends the rest of his life trying to get John back], wasn't this one of them? Woolsey taking over?
JOHN (glancing at Rodney): Circumstances were different.
KELLER: Still, it is a little unsettling. Maybe it's harder to change the course of events than we thought.
RODNEY: Well, I wouldn't worry about it. I mean, the fact that Sheppard's here makes all the difference, right?
JOHN: Woolsey wasn't the weirdest thing about that timeline.
KELLER: What do you mean?
JOHN: Never mind.
(Keller and Rodney glance at each other awkwardly.)
It does look like they're trying to set up McKay/Keller, but I hope Rodney's right, and the fact that Sheppard's there makes allllllllll the difference.