'This Is Us' Spills Season 4's 2 Huge Secrets in Finale

This is Us Season 4 concluded on Tuesday night, and it answered two monumental questions that have lingered throughout the entire season. One involved one of the Big Three's new partner, while the other involved a rift between two of the Pearson siblings. While there is plenty of road for the Pearsons ahead, these two points fill in some major gaps fans have been wondering about. (Spoilers ahead for This Is Us Season 4, Episode 13, "Strangers: Part Two.")

On Tuesday night's episode fans learned who Kevin Pearson (Justin Hartley) is having a baby with and what caused the major rift between Kevin and his adopted brother, Randall Pearson (Sterling K. Brown). Both reveals went down in the last few scenes of the episode as the entire Pearson family gathered to celebrate the first birthday of Kate Pearson's (Chrissy Metz) son Jack. At the party, Kevin deduces that Randall talked their mother, Rebecca Pearson (Mandy Moore), into taking part in a clinical trial that would cause her to move to St. Louis, far away from the rest of the family.

"I did whatever I needed to do to give our mother the best possible chance," Randall said when confronted, later adding, "Every one of you will regret not fighting for more [time]."

The brothers almost come to blows as Kevin grabs Randall's arm as he storms away. Randall gets heated, and Kevin belittles him.

"I'm not some out of shape purse snatcher," Kevin said, referring to an earlier incident. "You're not gonna sucker punch me."

Randall then storms out of the house as Kate's friend Madison (Caitlin Thompson) arrives. She then then tells Kevin about her pregnancy, which spurred from their one night stand together.

"I'm pregnant. You're the father," she said. "I'm sorry. I know I am a complete stranger to you. I'm just your sister's friend."

She added, "I've decided I'm going to go through this. You don't know my medical history, but this is kind of a miracle for me."

A shocked Kevin then gets up and stumbles outside, ensuring Madison that he just needs to step outside and take the news in.

"Madison, I think I'm gonna pass out," Kevin said. "I'm not walking away from this conversation."

Outside, Randall confronts a reeling Kevin and starts the argument up again.

"You think you know what's best for her cause you spent a day with her?" Randall says, referring to Rebecca's recent trip to New York City with Kevin.

They then have a massive blowup, challenging each others' positions in the family. Randall lashes out at Kevin for not being around, which Kevin attacks Randall for not being the protector that he claims to be.

"Where the hell did that come from?" Kevin says, then bringing up their dad Jack's (Milo Ventimiglia) death. "I would have walked through literal fire to save that man."

Randall then lays out an intense insult, saying, "He [Jack] died ashamed of you."

Kevin doesn't take that lying down and fires off a comeback as Randall leaves.

"I used to think the worst thing that happened to me was the day dad died," Kevin says before revealing that he now thinks "It was the day they brought you home."

The brothers are totally torn apart at this point, and Kevin has a moment of contemplation on the lawn. He then goes back inside and lets Madison know he is ready to be a father.

"I'm so sick of chasing ghosts. I'm tired of doubting myself. I'm all in, Madison. Whatever you need, I am all in," he says. "I wanna be a father. I think I'd be great at it. The love of my life will be my child."

Madison then adds one last twist, saying, "Children. It's twins, Kevin."

All past episodes of This Is Us are currently streaming on Hulu.