The Walking Dead is finally starting to reveal its Carl Grimes' replacements: Judith Grimes and Henry. The death of the series' teen protagonist, falling victim to a walker bite in season 8, was at the time one of the show's riskiest moves and biggest shocks. While other deaths have perhaps been more traumatic, few have been as unpredictable. While Glenn's ultra-violent braining was so poorly-received it marked a permanent loss of viewership, it was a near exact recreation of the character's death from the comics, so it had to have been anticipated by a significant portion of the audience. Same with other major losses, like Andrea, Dale and even Carl's mother Lori - while they were all tragic, their journeys paralleled those of their comic counterparts to some degree.
And even if they hadn't, The Walking Dead is known for its lack of plot armor - no one's really safe. The one exception to that rule felt like it could've been Carl. He's not only alive and well in the comics, but author and executive producer Robert Kirkman has said The Walking Dead is, in major part, a coming of age story set in the apocalypse. For it to remain so, someone has to be coming of age in order to provide that narrative perspective. The show killing him marked a significant deviation from that idea, and while TWD has never shied away from differing from its source material (it's embraced it, in fact), Carl Grimes' death leaves a lot of viable story on the table.
Nevertheless, Kirkman did promise that Carl's comic stories would still find their way into The Walking Dead. And, now, it would appear that the show has indeed found a way to adapt a few different threads from Carl's story at the same time using two other young characters.
Henry is Taking Carl's Hilltop Comic Story
After The Walking Dead's six-year time jump, Macsen Lintz's older brother Matt took over the role of Henry, as the character aged into young adulthood. "Who Are You Now" revealed the teenager still living at the Kingdom, but desperate to move to the Hilltop to apprentice with blacksmith Earl Sutton. After some hemming and hawing with his Ezekiel, the king eventually relents and Carol takes him to Hilltop. Once he's there, he faces some early disappointments as he discovers his crush, Enid, is seeing former Savior Alden later that night alienates some of the Hilltop teens while drunk on their moonshine. He ends up in a cell for his trouble and gets a stern talking to from Sutton. To anyone who's read the comics post All Out War, this should sound familiar.
After the two-year time jump in the comics, Carl finds himself bored and unchallenged living in Alexandria, so he relocates to the Hilltop to apprentice with Earl. He's not there for long before he also alienates his peers and winds up in a cell. It's there he meets Lydia, a young Whisperer (who has already been cast on the show), and the two start a romance. It's unclear if Henry will follow this path - it's a significant storyline for what's essentially a new character, and Season 9B teaser showed Lydia trying to convince Daryl to join her tribe, not Henry - but it's clear he's a Carl proxy at least in part.
Judith is Taking Carl's Alexandria Comic Story
The other Carl proxy The Walking Dead is using? Carl's little sister, Judith. In the comics, before he heads to Hilltop, it's revealed that Carl's been secretly visiting Negan in prison periodically to talk to the former Savior leader. He's in prison for life in Alexandria just as he is in the show, and Carl visits him because the two had a "friendly" relationship in the comics, too. This compelling aspect of Carl's character was adapted into a storyline for the preternaturally mature Judith, who visits Negan at his window and asks for help with her math homework because "it doesn't matter if you're a good or bad person on the inside. The numbers don't care."
While that's the only scene we've gotten with the two thus far, and Negan escaped his cell in The Walking Dead's midseason finale "Evolution," the two have clearly developed some kind of relationship that'll be explored further. Or at least it will if the show knows what's good for it. Those two were on fuego.