Liam Ellison is Katie's younger brother. He is in between eight and ninth grade over the summer when the novel unfolds. He is working out all summer because he plans to try out for the Quahogs football team before school starts.
It is Liam that tells Katie that Tommy Sullivan is back in town. Since he has been working out, girls Liam's age seem to be following him everywhere and calling the house constantly for him. When Liam makes the team, he and Katie get into a fight when Liam finds out she has been talking to Tommy after what he did to the team four years earlier.
