It has taken “This is Us” three seasons to unravel the mystery that is Jack Pearson. With the buildup of Jack’s time during Vietnam, we finally got our first look into how he got there, and his time there. This storyline has been played up since the end of season two, teasing us with little clips of what happened during the war. During this episode, we go all the way back to when Jack’s brother, Nick, was born and see their childhood together. Here are five new developments we learned about Jack’s darkened heart during this episode. Make sure you watch this week’s episode before you read, or beware there are major spoilers ahead, as we’re taking a journey into the past.

Jack’s brother is finally introduced.

“Hey little brother,” are the first words we hear from Jack at the beginning of the episode, as he goes to visit his brother Nick in Vietnam. We don’t see Nick’s face at first, as we immediately flash back to three weeks prior when Jack is leading his unit elsewhere in Vietnam as a sergeant. When we first see Nick on the day of the drafting lottery, he has the classic 1960’s long hair and beard. In the last shot of the episode, we see him almost bald, with no beard, clearly looking weak and tired. We learned last season that Nick does not survive the war, but how this happens is still a mystery.

We see a new side of Jack’s father.

During this episode, we see a side of their father, Stanley, that is not the drunk and abusive man that has been shown in previous episodes. At the time of Nick’s birth, Stanley is a kind, sober man. For the first time, it is recognized that the influence of being disappointed and abusive toward his children stems from Stanley’s own father, when he shows up to the hospital before Nick is born, clearly drunk and careless. After Nick is born, Stanley barely acknowledges him. In one instance, Nick tries to stand up for his mother when his father is being abusive toward her and is clearly intimidated to do so until Jack comes in to help.

Jack enlisted in the war because of his brother.

Growing up, Nick considered Jack to resemble Superman, seeing his brother as a hero and protector from the bad and the abuse of their father. On the day of the drafting lottery, Nick is clearly still reliant on Jack, showing how nervous he is that his number may get picked. Jack takes him to a bar to try and calm down his nerves, but the bar becomes completely silent as the numbers are read. They call by birthdays, and of course, Nick’s birthday, Oct. 18 is called.

Jack’s plan is to help Nick run away to Canada so he doesn’t have to go to war. After staying in a hotel overnight, Nick leaves Jack a note saying “It’s my turn to save the day, now,” and is gone.

A few months later, Jack’s family gets a letter from Nick saying that he has been “Article 15’d,” meaning he has been demoted in rank, for “reckless endangerment,” he is depressed, and probably won’t survive the war. In an instant, Jack decides he needs to go to Vietnam to help save his brother.

Jack’s heart condition may have lead to his death.

After deciding to enlist for the war, Jack goes to his doctor for a checkup and tells him about his plan. His doctor insists that this is a bad idea, due to Jack’s diagnosis of tachycardia, which is when a person has an irregular, fast heartbeat. Of course, Jack does not listen and enlists in the war anyway. We know that Jack died from a sudden heart attack after inhaling so much smoke from the fire, which we can guess is related to this condition.

Jack’s experiences in the war affected how he raised his kids.

The one scene that stood out in the episode about this key development was when one of Jack’s soldiers, Robinson is on the ground after getting shot. Before Robinson gets lifted out of the area to go home, he grabs both of Jack’s cheeks and just looks at him. The show then flashes forward to Jack doing the same exact thing to Randall, which we have seen before. This is only the start of Vietnam’s influence on Jack and what he has experienced.  

Jack’s storyline in this episode takes us into his inner demons, clearly making this one of the best episodes this season by far. From what the previews show, this is all that we will learn about Jack’s time in Vietnam for now. But what will we learn in next week’s episode? We will have to wait and see.

“This is Us” airs every Tuesday on NBC at 9/8c.

Email Hayley Solomon at [email protected] or follow her on Twitter at @hayley_solomon.