OK, 'This Is Us' Fans, We Need To Discuss Jack's Sister

This Is Us Season 4 began with an episode entitled "Strangers." And among the titular strangers was a blind singer who meets a nice girl in a coffee shop. As the episode went on, viewers witnessed their entire relationship, until the series finally introduced him properly: Jack Damon, Kate's son, all grown up. Now in the Season 4 finale "Strangers, Part 2," fans meet a few new faces, including Hailey, a docent at the Cohen Museum. But who is Hailey on This Is Us? Warning: Spoilers for This Is Us Season 4 follow.

When fans meet Hailey, she's at work, walking patrons around the museum and talking about the properties of paintings and art in a way that shows she loves the stuff. But she's also in an uncomfortable position. One of her co-workers is pestering her to go on a date. She turns him down, even as she admits he's probably her best friend.

Her co-worker, Zach, is disappointed, but not surprised. Hailey is hung up on some celebrity one-night stand she had, and Zach wants to know who. "Is it Leo?" he asks, in what might be the most prominent industry in-joke the show has ever made. (Leo Dicaprio is famous in Hollywood for never dating women over 25.)

But it turns out Zach isn't asking if Hailey slept with the man who was recently nominated for Once Upon A Time In Hollywood. That movie technically came out 30 years before their conversation happened. This is 2050, the furthest point in the This Is Us timeline, and Hailey's older brother, pop star Jack Damon, just had his first kid.

How does Jack get a younger sister? After all, it nearly killed Kate to have him. There's no way she's getting pregnant again so soon.

But Season 4's final episode has an answer to that. As Toby notes to Kate when she reminds him it's too dangerous for them to have another child: "The Pearsons have a pretty good track record with adoption."

Not that adoption is an easy route by any means. Kate and Toby will have a long road ahead of them in Season 5 to bring home a Baby Hailey to be sister to Baby Jack. But viewers know they will buckle down and go through with it, and that they'll succeed because Hailey is already here, at the hospital, thrilled to meet her new niece. Perhaps Kate and Toby will make their relationship work after all. Now all fans need to know is which celebrity she's trying to date.