Though This Is Us is a quiet family-centric dramedy, that doesn't mean it's without its fair share of twists. The reveals on the show are never crazy or unrealistic; they unfold naturally, giving the audience new information about the family they're just getting to know instead of pulling wild shocks out of left field. The obstacles and triumphs are grounded, and that's what makes them feel real. The first episode ended with the reveal that This Is Us was actually a family saga, and the second episode revealed that Jack and Rebecca are no longer together in the current timeline. Episode 3 has even more surprises in store. With that in mind, most This Is Us theories concern the same unanswered question: where is Jack?
The part of the show set in the past could feel resolved if the show let it – after all, audiences know all of the kids grow up and are mostly okay – but it's able to wring a surprising amount of emotion from the unknowns of the past. So far every important character has made an appearance in both halves of the story (past and present) except for Jack, the patriarch of the family. His fate is sure to be another big shocker this season, but what could it be? There really seem to be two potential options when it comes to theories about what happened to Jack.
Jack And Rebecca Divorced
This may be hard to imagine considering how strong their bond is and how deep their love obviously goes, but the seeds have been planted here. Episode 2 revolved around getting Jack to step up for his family; he was coming home late, drinking too much, and not giving Rebecca any of the support she needed to raise three children. Though he pledged to do better at the episode's end, these aren't issues that can be solved in an instant. Jack's battle with alcohol could have gotten worse instead of better, or maybe the strain of raising a family was just too much. Rebecca is with Miguel now (and he seemed pretty enamored of her even in the past), so it's possible Jack just wasn't able to do right by her and they separated. He could still be alive, but just hasn't appeared yet.
Jack Is Dead
However, some clues from the show's dialogue make it sound like Jack might not be around anymore. Kate clearly idolizes her parents, as shown in the pilot when she talked about wanting to be like her mother and marry a man like her father. If that marriage fell apart, then it's not as likely that Kate would be trying to recreate it. Also, while dealing with his biological father's impending death in Episode 3, Randall makes a comment that felt very telling: he said that his girls could have had a grandfather "all this time" if he knew about William before. That does seem to imply that they had been without one, making it sound like neither Jack nor Miguel had been in the picture for the last few years. Jack would be in his seventies in the present, and while Rebecca is still going strong and looking great, it's not unreasonable that he might have passed on. The reveal would definitely be a heartwrenching moment in a show that does them so well.
Both scenarios would be heartbreaking after watching this family grow and seeing how much they love each other despite everything, but they would both be realistic scenarios for a family to face.