Illumi Zoldyck

About

Illumi Zoldyck is the eldest son of the Zoldyck assassin family and Killua's manipulative oldest brother, whose Nen ability allows him to insert needles into people's bodies and alter their emotions, personality, and motor control. His distorted definition of love—controlling Killua entirely for his 'protection'—is the most immediately oppressive force in Killua's story, as the needle planted in Killua's brain made him flee from opponents who could kill him rather than fight. His cold, almost emotionless demeanor and his agreement to potentially kill Gon at Hisoka's request make him one of the series' most quietly terrifying presences.