In The Walking Dead's Season 8 midseason premiere, dying Carl (Chandler Riggs) looked back on his life. He remembered the words his mother spoke to him as she was dying — "You're going to beat this world" — and passed them along to his sister. And he also remembered the time he murdered a kid.
"Back at the prison, when we got attacked, there was a kid," Carl said to Rick (Andrew Lincoln). "A little older than me. He had a gun. He was starting to put it down and I shot him. He was giving it up and I just — I shot him. I think about him. What I did to him and how easy it was to just kill him."
That happened in the Season 3 finale, "Welcome to the Tombs." At that time, Carl had recently watched his mother Lori (Sarah Wayne Callies) die during childbirth and then shot her in the head to keep from reanimating. He was traumatized by the cruelty of the world he was living in, and it was making him nihilistic. Killing Jody (Tanner Holland), a surrendering Woodbury soldier, was the culmination of that.
After that shocking moment, Hershel (Scott Wilson) told Rick that Carl had murdered someone in cold blood. Rick realized just how hard his son his becoming, and that was the impetus for Rick being merciful and allowing the Woodbury survivors to come live with them at the prison, which Carl remembers as a turning point in his life. Rick showed him that there was another way. Rick has since forgotten, but Carl remembers, and wants Rick to get back to that.
"You put away your gun," Carl said. "You did so I could change. So I could be who I am now. What you did then, how you stopped fighting, was right. It still is. It could be like that again. You could still be like that again."
And in Carl's final moments, Rick promised him that he would see Carl's vision through. There was a lot of talk in the episode about honoring people who had died by living good lives in their image. It's kind of surprising that Jody's death has resonated so much throughout the years, but they're honoring him, too.
The Walking Dead airs Sundays at 9/8c on AMC.