This Is Us Season 4 once again created a mystery of the past that fans would have to solve. But unlike the question of how Jack Pearson died, this mystery incident hadn't happened yet when fans first saw it. During the Thanksgiving episode that ended Season 4's fall run, the series flashed forward to the Season 5 premiere, showing a very different Pearson family formation, where Randall is cut out by Kevin. So what was Kevin and Randall's fight on This Is Us about that ended their relationship? Fans thought they knew, but they might be wrong.
At Thanksgiving, Randall was dealing with a family crisis his siblings didn't know about yet. Their mother, Rebecca, was having memory issues. At the end of the holiday, she admitted to Randall she had a problem but made him promise not to tell anyone.
Randall did as she asked, going so far as to lie to his brother Kevin about why he took a plane trip. Fans put two and two together and figured this was a good theory for why they fell out. Randall must keep lying to Kevin, and their sister Kate too, until Rebecca's condition gets suddenly worse. Kevin and Kate get angry. They didn't know what was happening and missed out on enjoying Rebecca's final lucid months.
But according to This Is Us executive producer Isaac Aptaker, it's not that cut and dried. Besides, Rebecca has now told Kate as well. Kevin might get mad that he's the last one to know, but it's not like Randall is the only one carrying the secret of their mother's diagnosis.
Speaking to Entertainment Weekly, Aptaker said that what happens with Kevin and Randall is something that's going to build over the season's last five episodes.
That's something that's more going to be growing and building over the course of our remaining five episodes. But we'll definitely see some of the beginnings of that next week... There is much more of the story that we don't know. But there's certainly a brewing tension that we'll see over the next handful of episodes surrounding Rebecca and her mental health.
Keep in mind, when Kevin announced he would be a married father by the sibling's 40th birthday, Randall was skeptical. Their birthday was nine months away. Unless Kevin got someone pregnant that week, it probably wasn't happening. But Kevin has been serious about finding a date, and he's now slept with Kate's BFF Madison. Fans have a sneaking suspicion she will be the pregnant fiance Kevin talks about in the Season 5 premiere.
Randall may make the mistake of disapproving of Kevin's choices with Madison. He may also give some side-eye over a fast pregnancy. Add to that Randall not telling Kevin about Rebecca, and one can see a pattern forming, where Kevin feels disrespected by Randall's actions. It's a series of small incidents that can finally lead to one big blow up, the kind that fractures a family.