Whenever he goes onto late-night television shows, like Jimmy Kimmel Live, he’s always asked about This Is Us season 2 and the dicey issue of his character’s death. Obviously, he can’t spoil any major plot points ahead of the fall premiere, but he does offer the smallest of tidbits to hold over fans. During his latest appearance on Kimmel Tuesday, his new factoid was a behind-the-scenes reveal of how Sylvester Stallone agreed to guest star on the show.

This Is Us creator Dan Fogelman announced during the Television Critics Association Summer Press Tour that Stallone will play one of the movie stars in the Ron Howard war movie Kevin (Justin Hartley) is going off to film. As Ventimiglia explained, the producers had this idea to score a “big movie idol, icon” for the part. Since the actor played Stallone’s on-screen son in 2006’s Rocky Balboa, it fell to him to call up his old costar and see if he’d be willing to come aboard.

“When I pitched it to Sly, I said, ‘Listen, my son … You are his movie idol, but you gotta wonder where he gets it from. He gets it from dad.’ And so his involvement was a very big part of my character’s storyline, of Jack’s storyline, which meant a lot to me because Sly is one of my idols and I got to work with him,” Ventimiglia said.

We learned from Fogelman at TCA that Stallone’s character will act as a “father figure” to Kevin and he “hears what Kevin is experiencing in his life with his own father, and talks to Kevin a little bit about life and acting and memory and aging.”

In terms of how Jack dies, the lingering question of season 1, Ventimiglia could tell Kimmel some of the ways he didn’t die. For one, Jack didn’t die from giving birth. Case closed.

This Is Us returns for season 2 on Tuesday, Sep. 26 at 9 p.m. on NBC.