Then there's the sound of multiple deadbolts being unlocked, and when the door finally swings open, Bryan Adams is standing there! I mean, it's September! He's got hair, including a couple days' growth of stubble. He's also delighted to see Walter alive. Walter explains about being frozen in amber for twenty-one years (it's funny how they've told this story so many times it's almost casual, like "I went to California for the summer").
Then September spots Michael, and walks over, pulling the hood off his little bald head and crouching in front of him. Michael puts his right hand up, September his left -- September is tilting his head somewhat like the Observers do, but now his movements are laden with much more feeling; it's remarkable to watch.
Once everyone is seated in the apartment, September asks how they found him. Peter explains about the tapes Walter made in 2015, which led them to the radio that September left in the pocket universe, leading them to Michael (Olivia explains to September that "Michael" is what the couple called the kid), and voila. See? It's like a crazy video game!
"We've lost a lot. A lot of good people sacrificed themselves to get us to you," says Peter quietly, looking at Olivia.
Hey, but enough about their dead daughter, right? Walter wants to know what happened to September. So settle in, folks, because it's exposition time! September explains that before the invasion, he was arrested for his constant timeline-meddling, not to mention all his crazy shenanigans with Olivia and the Bishops. As punishment, his device was removed, and now he can't move through time or do the things he was able to do. If I may counter: Decent head of hair for a former baldie, so it's not all bad. (Assuming it's not a wig.) They experimented on him, calling it "biological reversion," and now he's no different from them. But it wasn't much of a punishment, he says, because he's always held this era in the highest regard. You know, I'd think I'd have preferred the '80s. Go to Minnesota and check out Prince and the Replacements in their heyday. Wait wait wait! Kill Hitler, and then go see the Replacements.
Anyway, Walter asks him why he chose the name "Donald." Was it for Sutherland? Fagen? Trump? Duck? Donald can't believe Walter doesn't remember; he picked it because they first movie they watched together was Singin' In the Rain, and he picked the name Donald O'Connor. Walter's delighted, and this seems to come back to him, especially how he would sing "Make 'Em Laugh" -- wonderfully, if he doesn't mind saying so himself -- in A-minor.