DEFINING MOMENT?

I honestly can't choose between the Christmas Present and the Gold Balloon Wedding! I think both of them define T&B for different reasons. The Christmas gift loomed LARGE for Todd, to the point where I really think it's a big part of the reason why he was able to forgive Blair's lie about the first baby...once he got past his anger, he couldn't help but see logically that the lie wasn't actually where they began...they weren't built on it. They were built on the friendship that came before it, and Christmas was a huge part of that. And laboulaie is right that it doesn't get nearly the recognition that it should get.

GBW has an advantage, though, in that it represented the future not just for T&B but for the family they were building. And it is the one thing T&B always call back to, consistently across all of the writing regimes.

Another important, defining moment I want to throw out there -- I don't know that I'd give it THE edge over the other two, but I think "Gravity of Love" is hugely important and should also get more recognition because of what it represented at the time (T&B actually being able to move past all the shit from 1996-1998, Todd flat-out telling Blair that he was "always" right there apparently even during his marriage to Tea, and Blair finally choosing Todd after weeks of being scared of her feelings) but also what it ended up representing, which was Jack. I think a case could be made that GOL sealed their supercouple status and meant they were going to be endgame. When Blair takes Todd's hand and they head toward the bed together, that's what it feels like: endgame.