Twelve-year-old Callum Hunt, known as Call, is the protagonist of The Iron Trial. Call is a moody and solitary child, qualities illustrated by his “perpetual scowl” and “suspicious gray eyes” (13). He is often excluded at his non-magic school due to his disability, which leads him to walk with a painful limp; he cannot participate in school sports and is picked on by bullies. Call’s father used to be a mage, although he stresses to Call that the world of magic is a dangerous one to avoid at all costs. Alastair warns Call, “The mages don’t care about anyone or anything except advancing their studies. They steal children from their families. They are monsters. They experiment on children. They are the reason your mother is dead” (80-81). For this reason, Call approaches the trial for the Magisterium (which is compulsory for all children who display signs of magic) with dread and fear. However, despite his father’s warnings to intentionally fail the trial, Call feels inherently drawn to the world of magic and the Magisterium.

At the Magisterium, Call finds purpose and companionship for the first time. He grows close to both Aaron and Tamara, Master Rufus’s other apprentices.