Walt Lopper, Jeremiah’s adoptive father, is a protecting and loving mentor to his son. Characterized as a brilliant but socially awkward computer consultant, Walt is a round and dynamic character whose defining trait is his deep, unwavering love for his son. Their relationship forms the emotional core of the novel and is a primary example of a found family. Walt discovered Jeremiah as an abandoned infant and chose to become his father. He is fiercely protective, a trait demonstrated when he confronts a hostile crowd booing the Eagles, effectively shutting them down with his authoritative presence; this moment also highlights one of the many ways that Walt teaches Jeremiah by example because he stands up for what is right. Throughout Jeremiah’s medical journey, Walt has provided similar guidance and important lessons about what it means to fight and win. Ultimately, he believes Jeremiah is extraordinary, and he is not afraid to share this with the boy. Walt tells him, “I couldn’t be a good father to some run-of-the-mill, ordinary kid. I would drive them crazy. I work on complex systems, Jer” (83). This statement reveals the love and admiration Walt has for Jeremiah, as well as their compatibility. Even though they are not biologically related, Walt is Jeremiah’s father in every other way.

Walt and Jeremiah share a lot in common, but the man also embraces his son’s journey toward independence as well as his own personal growth. As a former college pitcher whose career was cut short, Walt shares Jeremiah’s passion for baseball, providing him with his foundational knowledge of the game. He functions as a quiet source of wisdom and support, encouraging Jeremiah’s coaching ambitions while also tempering them with caution regarding his health. Walt’s character arc involves learning to trust in Jeremiah’s own strength and resilience, allowing him the independence to pursue his goals. This is exemplified when they play catch together for the first time in years. Furthermore, Walt’s budding romance with Dr. Dugan represents his own journey toward personal fulfillment. Over the years, he has been so focused on Jeremiah’s care that he has not thought much of himself. So, when one of his SARB robots shuts down, Walt has an epiphany: “You know, little guy, I can relate. I’ve got something I need to do, and I keep shutting down, too” (235). What Walt “needs” to do is accept love into his life, which is what he does when he goes into his room to call Dr. Dugan, presumably to propose. Ultimately, Walt leads again by example, showing Jeremiah that it is worth doing something difficult if it is for love and that family can also be the people you choose to bring into your life.

Franny Engers is a key supporting character who is both round and dynamic, serving as Jeremiah’s first friend in Hillcrest and a vital member of the Eagles. Initially, Franny is presented as guarded and sad, a stark contrast to Jeremiah’s determined optimism. Her withdrawn nature is a result of her father abandoning her family four years prior, a secret she keeps hidden for much of the novel. When Jeremiah opens up about his story, he expects her to do the same: “I wait for her to tell me and she doesn't” (222). Unlike Jeremiah, she cannot talk about her past and has not come to terms with it yet. However, he does get her to talk, which begins her own journey of healing. After their conversation, they agree to be best friends, and this relationship, as well as her eventual return to baseball, a sport she secretly loves and excels at, helps Franny move forward.

Franny’s recognition of Jeremiah’s inner strength is a pivotal moment in their relationship. She tells him, “But you don’t have a weak heart, Jeremiah […] I mean the other kind of heart. That one in you is strong” (125), showing her ability to see beyond his physical limitations to his true character. This bond, built on a mutual understanding of difficult family circumstances, allows her to slowly confront her own pain. Her decision to join the Eagles marks her re-engagement with her community and her passion, signifying a powerful step toward reclaiming her own identity. As a gifted player, she becomes a leader on the team, proving that strength can be found by facing the past and embracing community.

Ellis Grand, known affectionately as El Grande, functions as a classic mentor archetype. He is a static, round character whose wisdom and integrity represent the honorable history of baseball in Hillcrest, which makes him a foil to Coach Perkins. As Franny’s grandfather and a respected former coach, he provides a bridge between the town’s disillusioned present and its purer past. El Grande validates Jeremiah’s innate coaching abilities, recognizing his talent and officially making him his assistant coach, which gives the fledgling team legitimacy. His most crucial contribution is teaching the novel’s central lesson about Redefining Winning Beyond the Scoreboard. He shares a story from his own playing days about finding personal victory within a losing game, telling Jeremiah, “My team lost bad. But I won” (155). This philosophy becomes the guiding principle for the Eagles, teaching them to measure success by their effort, integrity, and personal growth rather than the final score. He is a pillar of the community, and his decision to coach the middle school team signals the beginning of the town’s healing process.

The Eagles function as a collective dynamic character, symbolizing the town of Hillcrest itself. Initially, they are a fractured and dispirited group of individuals, a “somewhat” team (48) that disbanded due to the toxic coaching of Coach Bordin, a figure who reflects the high school’s win-at-all-costs mentality on a smaller scale. The players are cynical about baseball and lack the numbers and motivation to form a proper team. Under Jeremiah’s guidance and El Grande’s mentorship, they transform from a resentful collection of former players into a cohesive and supportive unit. Their journey mirrors the town’s path from shame and disillusionment toward healing and a renewed, healthier love for the game. The team’s name change from the Muskrats to the Eagles is symbolic of this rebirth. El Grande notes that this change means “an eagle heart. Good eyesight. Fierce” (213). This description aligns with the town’s new values of empathy, good judgment, and strength. Within the team, Donald Mole serves as a notable individual example of this transformation. Starting as a player with immense heart but no discernible skill, he works relentlessly to improve. His game-winning catch in the final game is a triumphant moment that encapsulates the team’s essence: True victory is found in perseverance, dedication, and celebrating personal growth.

Benny Lewis is a minor but significant character who functions as the heart and spirit of the Eagles. Though he has developmental challenges that affect his communication, Benny possesses a unique and brilliant mind for baseball. He is a savant with an encyclopedic knowledge of player statistics and an uncanny ability to perceive the game on a deeper level. He is the first to recognize Franny hits better when she is angry and intuitively knows Donald Mole should be put in to bat at a critical moment. Benny’s presence reinforces the idea that strength comes in many forms. While he cannot play in a traditional sense, his contributions as the team’s unofficial statistician and mascot are invaluable. His pure, untainted love for the game stands in stark contrast to the cynicism that has infected Hillcrest, and his joyful cheers of “Yay!” (163) serve as a constant reminder of what baseball should be about: uncomplicated and fun.

Coach Delmar Perkins, the story’s antagonist and foil to El Grande and Jeremiah, is a flat character who embodies the destructive “win-at-all-costs” philosophy. His actions, giving performance-enhancing drugs to his high school players, are the source of Hillcrest’s collective trauma. Additionally, he denies any wrongdoing. In the transcripts from the preliminary hearing, he says, “[T]he pills I gave them were vitamins. I don't know what they got into on their own, but they didn't get steroids from me” (201). This denial so deep into the investigation emphasizes that Perkins is only concerned about himself, willing to place all blame and responsibility on the boys when he is truly at fault. Consequently, he represents the potential negatives of coaching, prioritizing championships, and himself, over the well-being of his players.

Hargie Cantwell is a symbolic figure and the tragic victim of Perkins’s ambition. As the Hornets’ star pitcher, he is the face of the town’s baseball glory. His sudden death from a steroid-induced heart attack shatters this illusion, forcing the community to confront the dark truth behind their success. Together, Perkins and Hargie represent the corrupt system that Jeremiah and the Eagles work to overcome, a system where winning is valued more than integrity, health, and life itself.

Dr. Sarah Dugan is a key supporting character who acts as Jeremiah’s new cardiologist and a positive adult influence. As an adoptee herself, she has a unique and immediate understanding of Jeremiah’s life, telling him, “A nose doesn’t make you part of a family, Jeremiah. It’s the heart” (79). Her statement emphasizes that it is not similar biological appearance, but love and connection that make a family, highlighting the power of found family. Furthermore, she is both a skilled doctor who manages Jeremiah’s complex health needs and a compassionate figure who supports his ambitions. Her developing relationship with Walt promises to complete their family unit, providing Jeremiah with the stable, loving, two-parent home he has never had. Dr. Dugan represents healing, both medically and emotionally.

Bo Engers, Franny’s older brother, is a minor, dynamic character who reflects the disillusionment of Hillcrest’s youth. Having had his own dreams of being a Hornet crushed by a pitching-arm injury and the toxic environment of the former middle school team, he is cynical and withdrawn. His connection to Hargie Cantwell makes the scandal deeply personal for him. Throughout the story, Bo’s gradual re-engagement with baseball, first agreeing to help with the middle school team and then through a practice game with the remaining Hornets, charts his own slow path toward healing, which mirrors that of the community.