Nate grabs Trip outside the Nassau County ER, pointing out that he not only abandoned Serena to the literal wolves, but also moved her into the driver's seat, which is like the only no-no you can expect Nate to remember. That's such a Maureen move, jostling Serena's spine like that. Trip whines that he called 911, and Nate explains that not only is that a joke, but also welcome to how he no longer hero-worships Trip. Because fucking around on his wife with the sudden love of his life and acceding to everything Grandfather ever asked about him didn't do the trick. He assures Trip that he'll be speaking with the police quite openly about this unforgivable shit, and Maureen once again appears from the shadows. She's getting really good at that.
"...The truth is that Trip was with me." Trip is like, "I told you to stay in the car! I want to see my girlfriend and everybody keeps bothering me!" and Maureen informs him that he is not in charge and will never be in charge again, tells Nate that Grandfather William has Trip's back on this and has the Nassau County police in his pocket anyway, and that nobody will believe Serena's story because she is a drunken whore. There's a certain resigned sadness to her when she heads back to the car, summoning Trip with a whistle, and he almost follows before coming back to beg Nate with Crazy Sad Eyes to help him get in to see Serena. Nate drops him with a punch, because it's been months since we saw him pop somebody's clogs, and Maureen is just disgusted by everything, and GG calls Nate a hero, and it's all sort of amazing, especially when you consider how Trip and Maureen are the Ghosts of Christmas Future of if Nate and Blair had stayed together, and how much neater Nate's become this year than ever before.
Serena immediately apologizes to her mother when she wakes up, and they agree that Rhodes Women have to learn the hard way, and then Lily fudges around about how she tasked Rufus with getting Serena's "health insurance papers" out of her desk before coming out to see them. This information is prompted by S asking if Rufus is there, which my loving heart would like to think is because S is fond of Rufus but is obviously just Serena's shorthand for asking if Rufus has left Lily yet. Lily stammers and acts guilty and Serena gets disgusted about how no matter how often the entire UES screams at her about making the right decision, Lily is still weaker than she is, and fully turns her eyes to the ceiling and asks to be left alone. Lily leaves, guilty, and pats Blair on the arm on her way out.