Derry's residents suffer an unusual form of amnesia when they leave Derry in IT and IT: Welcome to Derry, but they unexpectedly remember events again due to a key reason. The brand-new HBO Max prequel series revisited Derry and the secrets tied to the ancient evil that takes the form of Pennywise the Clown (who is not the main character of IT: Welcome to Derry), circling back decades before the Losers' Club's imminent clash against the killer clown in 1989 (IT: Chapter One). One of the key questions surrounding Derry's connection to Pennywise is why residents keep forgetting the horrors that occurred within the town when they leave.
IT: Chapter Two established that the Losers Club (except Mike Hanlon) forgot everything that transpired in Derry, further proving that Pennywise's hold in the town is strong. IT: Welcome to Derry Episode 3 pulled back the curtain on the town's horrific history while also providing more context on why certain people forget.
Why Derry’s Residents Forget the Past, Explained
Pennywise's "supernatural hold" over Derry is the main reason why residents and anyone who visits the town forget everything that happens when they leave it. This ancient evil basically holds the town hostage without Derry residents knowing and enforces amnesia as its defense mechanism to ensure that IT's 27-year cycle continues without outside interference.
IT: Welcome to Derry Episode 3 provided a brief explanation of why the town forgets during a conversation between Frank Shaw (James Renar) and Rose (a Derry native portrayed by Kimberly Guerrero). The episode's opening scene established that the pair first met in one of Pennywise's past cycles (presumably in 1908, based on their ages), where Shaw was attacked but was saved by Rose.
However, a few days later, Shaw left Derry, and he completely forgot what had happened, and he only remembered when he returned to Derry. Rose pointed out that all memories "just [seem] to fade" when one leaves:
Frank Shaw: "I mean, I didn't remember any of it, You, this town."
Rose: "You're not the first... No matter how long you spend here. The further away you get, the more it all just seems to fade. Some would say it's for the best. I don't know. It has his charms. But do you remember?"
Frank Shaw: "Not much. My father, life on the base? But mostly. I remember you."
Rose: "It was one summer Francis, we were 12. I doubt you even remember my name."
Rose's explanation was consistent with what Mike Hanlon told Bill Denborough in 2019's IT: Chapter Two. In the sequel, Mike pointed out that the "farther away" a person is to Derry, "the hazier it all gets," further proving Pennywise's influence over the town:
"Something happens to you when you leave this town. The farther away, the hazier it all gets."
As it turns out, leaving Derry means that Pennywise's hold will no longer be attached to that person, and this supernatural effect has limits if an individual removes himself from the ancient evil's killing ground. This could also explain why the town's residents are oblivious to the accidents and missing children.
Here’s How Derry’s Residents Remember Events Again
Returning to Derry triggers recall for former residents of the town, and this is how they remember all the trauma and the nightmarish things they encountered.
IT: Chapter Two revealed that Mike Hanlon was the only one who remembered everything because he stayed in Derry while the other members of the Losers' Club left. It's as if IT wanted Mike to remember so that he could contact the other Losers and fulfill its revenge plot against them. The Losers would then eventually remember when they return to Derry (read more about every Welcome to Derry character related to the Losers' Club here).
In Stephen King's novel, a mere mention of Derry is more than enough to trigger the return of the memories. For example, when Mike mentioned Derry to Bill during one phone call, all the memories of what had happened in their childhood came flooding back.
In a sense, forgetting what happens in Derry when you leave the town is a metaphor for suppressing childhood trauma, and going back there triggers everything back, and one needs to confront it as an adult.
