Last night's shocking This Is Us fall finale left us asking a lot of big questions.
We were under the impression that Jack's younger brother, Nicky (Michael Angarano), died during the Vietnam War, but Tuesday's episode revealed that that actually wasn't the case: Nicky is alive. Years after the war ended, an older man wearing similar glasses to the signature thick-rimmed lenses Nicky wore is seen coming home and checking his mail, which was all addressed to a Nicholas Pearson residing in the small town of Bradford, Pennsylvania.
Milo Ventimiglia spoke with ET on Wednesday about the game-changing twist, sharing that he "found out pretty early on" that Nicky was alive and well, and did not perish in the war.
"I remember when there was a discovery that Jack had a brother and the idea of Jack's brother's assumed death in Vietnam, but known for a while. Even out in the world doing press, I kept saying 'Jack lost his brother, Jack lost his brother, Jack lost his brother,' but I knew pretty early on," Ventimiglia told ET over the phone.
"I think it's very This Is Us," he said of the twist. "Our show doesn't quite operate the same and we do have our family mysteries and history to discover, so I thought it fit very much with how the show usually works and at the same time, it asks so many questions of Jack. I think people at this point are really looking forward to knowing what happened, especially if his brother is still alive."
During the war, Nicky was struggling with substance abuse, which prompted Jack to declare that he was going to get him sober again, to the chagrin of his younger brother. It was a potentially fatal boat explosion that led many viewers to presume that Nicky was on that boat, a new mystery for the show to unpack once it returns in January.
"I really can't say much more," Ventimiglia said, playing coy. "Did Jack know that his brother died? Or thought his brother died? We don't know."
The 41-year-old actor promised, however, that the payoff to that specific question will be addressed pretty quickly.
"It's mystery on mystery but the discovery of that comes pretty quick," he assured. "Shortly after, when we come back in January, we complete that story."
Ventimiglia was on set Wednesday morning, so he wasn't able to fully engage with the fans' reactions to Nicky's fate and what this means for the rest of the Pearson family. But he noted that one of the writers mentioned that the writers' room has fully embraced viewers' speculative theories.
"When I was on set, one of our writers was talking about some emails that had been circling the writers' room about speculation and theories and all of what really happened," he said. "It's fun that the audience engagement after one of the mysteries, like, of course, Jack was discovered dead, how did he die? What happened? It's nice to know people are engaging."
Prior to the This Is Us fall finale, Mandy Moore shared a tearful Instagram Story, where she was seen getting emotional over the episode.
"What was beautiful about the episode last night was it was all of us. It was not just a Jack-centric story or focused on one other character, it kind of really tied everyone together," Ventimiglia praised. "It's something that the show does well -- balancing several storylines that also are all connected and connected in different ways for different characters. Now, there's something special about this show that will always stay relative to family and our differences but what brings [it] back together."
This Is Us returns Tuesday, Jan. 15 at 9 p.m. ET/PT on NBC.