'This Is Us' Newcomer Michael Angarano Warns Nicky's Death Is 'Tragic' (Exclusive)

The 30-year-old actor also talks to ET about his upcoming indie film, 'In a Relationship.'

If you thought Jack's death was heartbreaking, more tragedy awaits on This Is Us. 

We've only scratched the surface on what happened to Jack's brother, Nicky, and when ET caught up with Michael Angarano, who plays the younger Pearson sibling, he warned that what transpires in the lead-up to his character's death is heartbreaking and harrowing. In fact, it's Jack and Nicky's complicated brotherhood that Angarano says shapes Jack as a father to the Big 3.

"You'll definitely understand why Jack is the way he is and the way especially that he speaks about his brother, Nicky," Angarano told ET's Courtney Tezeno at the In a Relationship premiere on Tuesday. "Everything will become really clear really soon."

While Jack died from a heart attack following complications suffered during a house fire, Angarano hinted that Nicky's demise during the Vietnam War is much more dire. 

"It's pretty tragic," the 30-year-old actor teased, before offering this stern warning, "All of it is pretty sad."

Angarano spoke to ET following the "Vietnam" episode that aired Oct. 16, which marked his much-awaited introduction to This Is Us audiences. It was revealed during the hour that Nicky's birth date was the fifth chosen during the televised lottery, that Jack had a plan to help his brother escape to Canada and that Nicky decided to be his own hero and serve in the Army.

“There’s one thing that you can really see in this episode that really weighs on Nicky: that he is Jack’s brother," Angarano told ET at the time. "He feels the weight of being the younger brother, always being protected, always being looked out for. It’s Jack’s plan. There’s that classic sibling dynamic in which the younger brother’s like, 'Let me go. I can do this. I can be my own person.'"

"It’s also that co-dependent relationship that he has because he needs it. There’s a part of him that doesn’t know if he can stand on his own without his brother’s help. There’s also the fact that he’s used to his father being inconsistent and negligent and abusive," he added. "There’s going to be that effect on his personality that he’s not even aware of. The fact that he’s chain-smoking and he’s at the draft and needs to take shots and drink... He doesn’t understand these things about himself yet."

It's an exciting time for Angarano, who also stars in the upcoming indie film In a Relationship opposite Emma Roberts. The film, directed and written by Sam Boyd, follows two couples who find themselves in opposite stages of love.

"I'm friends with Sam Boyd, the writer and director, and I was a fan of the short film that he made of the same name and he always told me that he just wanted to make a romantic comedy for our generation and what that meant. What I took it to mean was that it's messy and it's not your typical three-[act] structure and there's not some grand gesture. It's about people who don't really know what they want or why they want it and so it's about people sort of finding themselves and dragging somebody along the way."

"All the characters want is to be happy," he continued. "That's kind of goal No. 1 and so that comes across as selfish or confused or sometimes two people pleasing [each other] and they're just wanting to be happy. That's really the goal of each and every character in it."

Angarano praised his friendship with Roberts, who plays his onscreen love interest, for creating instant chemistry. 

"We've known each other for a long time and something like this, we're playing a couple who's been together for five years and deciding that we don't want to move in together. It was just really natural from the get-go," he said. "Emma is great because she's really smart and we just had a lot of fun."

In a Relationship is in limited release on Friday, Nov. 9. This Is Us returns Tuesday, Nov. 13 at 9 p.m. ET/PT on NBC.