"Perso test?" his younger sister Lina asked from the doorway, balancing a stack of photocopied exercises. In their house, "perso" had become shorthand for the personality questionnaires that accompanied technical exams — a test of who you were as much as what you knew. It was the part that unnerved Slimène most; numbers and formulas obeyed rules he could practice, but "perso" demanded an answer he didn’t always recognize.