The scarred Son who trains Darrow to brutal perfection and recognizes in him a rage that mirrors her own.
While Mickey rebuilds Darrow's body, Harmony hardens it, driving him through concentraction machines and high-gravity in a grimy gym beneath the club — "if you're not vomiting thinking about a workout, you're not trying" — racing him across simulated Mars, Earth, and pre-colonial Luna. She insists he be flawless, for the other children of the Institute will butcher any weakness, clashing with Mickey who fears she will break his masterpiece; Dancer sides with her. As Darrow's remade strength grows he surpasses even this hardened woman of the mines until she seems a child beside him.
They speak little, but a primal kinship forms: Darrow senses that behind her scarred, space-cold face is someone who lost a loved one, a rage as consuming as his own, and it is the one thing about her he does not resent.
A woman with a face divided: one side milk-pale and beautiful, the other a distended run of steam-burn scar; cold glittering eyes, uneven bottom teeth, knives in her boots; hardened and quick, though outstripped by Darrow's remade body.
Darrow's brutal trainer and the Son whose grief-born rage most mirrors his own.