'This Is Us' Explores Jack Pearson's Relationship With Brother in Vietnam-Themed Episode

This Is Us' big Vietnam episode revealed many moments that led Jack Pearson to become the man beloved by fans of the series, told through the perspective of his relationship with his brother Nicky.

The episode begins with Jack arriving at the army base and finds a man filing up water bottles. Viewers don't see his face but he says, "hello brother."

The episode then flashes back three weeks, finding Jack with his fellow military talking about what they plan to do when they go back home at the end of the war.

That night, Jacks group is ambushed by enemy forces after one of his people steps and triggers a bomb. He covers for them as they attempt to escape and he hears as another one of his friends is injured in an explosion. The injury leads to him being sent home early, and the two friends share a sweet moment before he is helicoptered out.

Later, Jack is sent to a village and he watches the other soldiers play in a lake. He is stationed in a village where only women and children live and he is to stay there for a few weeks.

When the helicopter arrives with more supplies and the sergeant, Jack asks if he might be able to travel to another base to see his brother, but he says no given the squad's lack of discipline. However, when he notices that the village is in top shape and everything is in order, he allows Jack to go.

The series then flashes back 14 months to when Jack's mom and Jack received a letter from Nicky (Michael Angarano) saying he had been disciplined by the army and that he thought he was going to die at war.

The letter leads Jack to enlist to go to Vietnam so he can go take care of his brother, despite his heart problems.

"He's there now, and he's struggling. I just need to be where he is, even if I can't get to him... I just need to be there. He's my little brother doc. It's my job to take care of him. That is my only job," Jack tells the doctor.

The show then flashes back one more time to before Nicky was drafted for the war. Nicky feels bad for always having to be saved by his older brother. When his number is called in the draft lottery, Jack tries to convince his brother to run away to Canada. Despite the plan to run in motion, Nicky leaves Jack at a motel and heads to Vietnam.

After a sequence showing the Pearson brothers' abusive childhood and Nicky's birth, the episode returns to Jack finally meeting his brother in Vietnam, finally showing his face.

The Vietnam story seems to be far from over, as the episode did not reveal how Nicky died during the war. Kevin (Justin Hartley) will also be heading to Vietnam later in the season, which may bring more answers.

Nicky was first revealed as Jack's brother in season two, in a flashback scene of when they were children waiting in a car as their father went into a bar to drink. In the same episode, Jack (Milo Ventimiglia) is seen looking at a photo of Nicky as an adult in Vietnam.

Later in the series, Jack reveals to Randall and Kevin that his brother died in the war.

For the special Vietnam episode, creator Dan Fogelman teamed up with Vietnam veteran and novelist Tim O'Brien, writer of The Things They Carry, to write an authentic portrayal of Jack's experiences in the war.

"...I just finished actually writing an episode with him that's an entire Vietnam Jack backstory episode, early in our season," Fogelman told Deadline earlier this year. "That's going to be really incredibly exciting and unusual."

Jack's time in Vietnam has been one of the series' most intriguing mysteries, along with how Jack died (in a house fire), which was revealed during the show's iconic post Super Bowl episode.

This Is Us airs Tuesdays at 9 p.m. ET on NBC.