We try to shove life into categories at every chance we get. The tighter we can squeeze it into a regulated space, the more it seems like we — not god, or chance, or entropy — are the ones who get to control it. We experience childhood, and middle school, and college. We are young professionals, and newlyweds and then maybe the cycle starts again. This week’s episode of the family drama This Is Us opens with the most basic of these time constraints: the birthday. In the opening shot, obviously made to look like it was filmed on an old family camcorder, we see our close-knit family playing pin-the-tail-on-the-donkey. They are exuberant, jovial, rosy. With three children and a father all born on the same day in a calendar year, there is truly a lot of celebrate. Much of this episode, “Three Sentences” deals with the next birthday the kids have: their tenth. The kids call a “meeting” with Rebecca (Mandy Moore) and Jack (Milo Ventimiglia). They feel old enough now, and want to each have their own birthday parties instead of the single combined party. They want to individualize. Kate wants a Madonna birthday party, and Kevin wants a Princess Bride themed party, and Randall doesn’t care at all about his birthday party. Over the course of the episode, we watch as the parties unfold according to the different personalities of the kids. Kevin’s party becomes the attraction while Kate and Randall’s parties are very small whether they care (Kate) or not (Randall.) But throughout the course of this episode, the true intrigue lies in the periods of life that This Is Us has remained shrouded in mystery for the entirety of its first season. Midway through season one, it feels like we know a lot about this core group of five people whose lives orbit each other so closely it’s impossible to divide their stories completely from one another. We know the show’s present day because it is progressing forward in front of our eyes. Kevin (Justin Heartley) is a successful actor trying to get some credibility doing a play. Kate (Chrissy Metz) is also successful and still fighting a lot of the same demons she faced as a child. And Randall (Sterling K. Brown) is successful in work and love, with a beautiful wife and two daughters. Because of the way the show is structured, we also know a good amount about the children’s most formative years (from birth to 10) and the two flawed but truly loving parents who raised them. For a while, that has been enough to keep the show gorgeously shot and easily accessible and emotionally resonating. But tonight, the show gave us a taste sweeter than ever before of what might lie between those two narratives, of more life stations and decisions that could twist everything we think we know about these characters. The most interesting story this episode is with the hot actor brother Kevin’s story. For most of the season, Kevin has been, well, shallow. Though the show (and even his character) continually argue for why he has more depth than his perfect body might display, he hasn’t really had the chance to shine beyond his beauty. In this episode, though, Justin Heartley really brings his character to an entirely different universe, portraying Kevin as distressed and conflicted and desperate to find a space in the world where he can love someone well. This desire manifests itself through a complicated love triangle Kevin is trying to navigate. He refused to date his ex-co-star Olivia (Janet Montgomery), ruining that relationship. And in the process, downplays his interest in his playwright, Sloane Sandburg (Milana Vayntrub) ruining that relationship as well. Usually, the best person to help Kevin with his problems would be Kate, but — because she spends the whole episode at an “immersive fat loss camp” in the Adirondacks hitting the floor with drumsticks and wandering around — she can’t help him. Instead, Kate deploys her fiancé Toby (Chris Sullivan) to help out her lost little brother. Toby, as we have already seen, is the king of grand gestures. He tells Kevin that he’s seen “every rom-com ever made.” Wanting to help Kevin win back the girl of his dreams, he gives him simple instructions: Close your eyes, picture the love of your life, and think of the three sentences you’d want to say to her. In the next scene, we see Kevin emerge from the car. Who will he pick? Sloane? She’s quirky and funny and artsy. They’re in a beautiful play together. Olivia? She’s mysterious and British and seems kind of crazy in the way that only true artists can be. It turns out, neither. The door swings open and there is a blonde standing in maroon-colored scrubs with her hair half pulled back from her face. It’s the first true plot twist the show has given us since the first episode’s shock, and it’s deployed beautifully. There’s no reason at all to believe that this woman, this “Sophie” is a major character in the drama of this family’s life, and yet here she is. From the episode’s flashbacks, we know that Sophie was Kate’s best friend at age 10, and that Kevin told his parents he “loved her” even then. From Sophie’s own mouth we hear the stunning “ex-husband” and learn that she and Kevin haven’t spoken in over a decade. There’s a whole life stage of Kevin’s, then, where he was married to Sophie, his childhood sweetheart, that we not only don’t know about, but up until this point had no reason to know existed. In the next scene, we see a flashback to Jack’s funeral. For half the season we have known that Jack is dead in the present, but not when or how his death occurred. In this episode, we get hints that the kids were in their teens, but also that all the banter Jack and Rebecca have early in the episode about potentially having another kid (that they both eventually squashed) might not have just been banter. As the flashback to the funeral pans across the Pearson family it shows Randall and Kate and Kevin before dropping a few feet to hazily take in the profile of a shorter, younger girl holding on to Kevin’s hand; a hint that another Pearson child might potentially exist. In one swift motion, This Is Us reminds us, the viewers, that though we are now familiar with the Pearson family, there is so, so much about them we simply do not know.