Dan took Georgina to Tuscany so they could be super gay for no reason, and he screwed Nate over on the various "chapters" he is writing about everybody else on the show, but now even that has spiraled out of control and he's writing multiple chapters about people and sending them hither and thither. Hint: All of them are about Serena because everything is about Serena because spoiler alert, everything is literally about Serena. In a way, which the show has been saying for six years, actually has nothing to do with Serena. Which I always thought was the higher point, but the actual higher point is so much nastier -- and more beautiful -- than I could have imagined, even in the show's heyday, that it works out.
Nate thinks he knows who Gossip Girl is, he has no idea who Gossip Girl is.
Serena thinks... nothing. It has never mattered what Serena thinks and it will never matter what Serena thinks. Which is why she has always been my favorite character: If I sat you down and said, "Imagine what it would be like if the whole universe sat you down and said be pretty, be little, stop talking, stop thinking," you'd know what it is like to be a teenage girl. And bonus, you'd know what it's like to be a gay man, or a straight woman, or anybody that is not the default white straight man. You'd kind of know what Serena is about, but you still wouldn't really know what Serena is about, because the whole point of Serena is that there is no point to Serena. Just an infinity of Daisy Millers, standing on the shoulders of an infinity of Daisy Buchanans, alternating all the way down.
Blair used to balance that out, until Chuck, and now they balance out each other. They have their own little TV show inside the TV show of Serena. A thing Blair has always secretly worried was true, until she put her show inside the Chuck show, and now she's happy as a bee.
Everybody Else, from Lily to Rufus to Scott to Bart to Ivy to Jenny and Vanessa and Juliet and Carter Baizen, is a piece of this puzzle. Sometimes they're real, somebody they are not real. Much of the last three or so seasons has had to do with various people that are almost Serena but not really -- Ivy, Lola, Juliet -- but are connected with her closely enough -- William -- that they matter. But only kind of, and never for very long.
Blair and Chuck have killed his father, finally, watching him slip quickly over the ledge and down into the streets below. Blair calls Georgina, downstairs, who arranges through activities presumably scary and possibly sexual to get them into the trunk of their dumb limousine and away from the scene of their crime. If you're thinking this is an easy one-shot -- Chuck clearly would only kill his father in self-defense, Blair is the only witness to any of this -- you're right. The murder of thrice-dead Bartholomew Bass is no big deal.