- "A kid—Isaac’s brother, I assume—darted out from the kitchen. He was maybe ten, wiry and over energetic, and he kind of skipped across the living room before shouting in a really good imitation of Isaac’s voice, “KILL MYSELF.”
- — Hazel Grace on Graham
Graham is Isaac's presumably ten year-old younger brother. He is described as wiry and energetic. He is first seen when he interrupts Isaac and Hazel Grace as they play the voice-operated video game edition of The Price of Dawn. It can be inferred he is mischievous, as he imitates Isaac during the game and says "KILL MYSELF" in order force Isaac to die in-game. Isaac then tells Graham to get out, to which the little boy "laughs giddily" and skips down the hallway.
Isaac and Graham seem to have a normal brotherly relationship, though it can be inferred Graham likes to annoy Isaac and cause trouble. Isaac seems to be tolerant of his brother, though unfazed by his tricks as if he plays them frequently.
- Graham is real, he is Esther Grace Earl's younger brother.