An intelligent young boy with Morquio syndrome who befriends Max; he is interested in various fields of study and imagines himself as part of a great adventure with Max.

Max's grandmother, who initially fears him due to his resemblance to his father but grows closer to him as she sees his friendship with Freak.

Max's grandfather, who is protective of his family and wary of Max's potential similarities to his criminal father; he becomes more supportive of Max as he proves to be a caring friend.

Kevin's kind and generous mother who worries about her son; she is initially wary of Max but welcomes their friendship.

Max's father, who is notorious for his criminal past and whose influence looms over Max's life due to his violent history.

A woman living in the tenements who interacts with Max and Freak during one of their ventures; she has a complicated relationship with the boys but shows some redeeming qualities.

Leader of The Panheads motorcycle gang, who interacts with Max and Freak and has connections to Killer Kane, displaying a fear-driven nature.

Freak and Max's English teacher who is initially overwhelmed by their classroom dynamic but gradually recognizes their unique way of learning together.

The principal of Freak and Max’s school, who is concerned about Max's well-being and offers him supportive reassurances.

Freak's attending physician at the hospital, who shares insights into Freak's condition and his imaginative outlook.