Welcome to Derry May Have Solved a Lingering Pennywise Enigma
Pennywise's impact on the young residents of Welcome to Derry shapes them long into adulthood, twisting them into the very adults who perpetuate the town's cycle of hatred alive. The creature preys most easily on children from broken homes — children who often grow up to repeat the identical behaviors as their guardians. However, the Hanlon family distinguishes itself as a rare example of a family unit that never splinters, which could clarify why Mike, even after choosing to stay in the town, persists as the sole member who never fully falls under Pennywise's sway.
The Hanlon Family's Unique Resistance
In episode 4 of Welcome to Derry, Leroy Hanlon at last grows more aware of the supernatural forces enveloping the community, particularly when the entity begins tormenting his child, Will Hanlon, during their angling excursion. The Hanlon clan consists of a small number of grown-ups who are cognizant that something is amiss with the municipality, notably Leroy, who was shown to be sensitive to the Shining when he was capable of sensing a fellow psychic's employment of it in the third episode. Later, Leroy sees one of the clown's trademark inflated orbs outside his house. The ability, coupled with his failure to experience terror, along with the base of his household, could be why he's able to see Pennywise's hauntings. However, consider if that shining is generational, and one of the reasons Mike is among the few individuals in Derry who resisted succumbing to the town's malevolence?
The boy is a member of the group of kids at his school being terrorized by the clown. All his school friends come from dysfunctional families, with caregivers who don't believe they're being haunted. The cause Will is being pursued is because of the cruelty of the town, paired with his likely receptiveness to psychic abilities, which makes him susceptible. The Hanlons are fundamentally strangers in Derry during the early sixties, which lends itself towards the household sensing anomalies exist about the town from the onset. They also have a solid base that isn't fractured, unlike the residents who originate in the town, with relationships that have deteriorated internally.
Historical Context
Based on the original book, we know the young Will will find himself at the Black Spot, where the psychic will rescue him from a blaze that the local KKK members of the community will cause. In the recent movie, we see that he has a boy named Mike and that Will ultimately dies in a fire, with his father outliving his own child and taking his grandson in. The public account in the film is that Mike's parents were on substances, but given our current view of Will in the series, that's hard to believe. Maybe the shy boy, once he grew up, turned to alcohol to free himself of the torments, or perhaps the rotten town got to him first, with the hate group ultimately finishing the job it began years ago. Be it via the fear of Pennywise or via the cruelty of the town, seeded by Pennywise, It eventually gets the final victory on him.
The Father's Evolution
This chain of events would explain how the elder Hanlon changes so drastically from what we witness in It: Chapter 1 and the prequel. In his older age, he appears bitter and much stricter with his parenting. Since he outlived his own offspring, it's understandable to see such a drastic change. Nonetheless, his words hold greater significance since we are aware he's seen Pennywise's hauntings and the impacts they had on his son. In the opening scene of It, we observe Mike pause to use a bolt gun on a sheep at Leroy's farm. His grandfather chastises him for delaying and offers an analogy that results in a kill-or-be-killed situation.
“You have two options you can be in this world. You can be in the open like we are, or you can be trapped inside,” he states as he gestures to the sheep. “You dawdle indecisive, and someone is going to make that choice. Except you won't know it until you feel that bolt between your eyes.”
Looking back, this could be a piece of foreshadowing, a lesson he wishes he had told his own child. Perhaps he desires he had done something in his youth, but for some reason, he was unable to avoid the sickening attraction of the town.