Nauk was forced to join the Legions when he lost control of himself and attacked a merchant. He was given the choice of military service or criminal punishment.
Nauk was in the War College the year Catherine Foundling temporarily entered it. He was part of Rat Company, and in Catherine's first training battle he was one of only a handful of people to escape Juniper's opening attack.
Nauk is described as being intelligent, but preferring to be aggressive and take the initiative rather than wait and let his enemies take initiative.
He also has an unusual difficulty in controlling the red rage, which is something of a liability in one of his rank. However, he is otherwise competent and always had Nilin to cover his personal weaknesses.
Nauk had a very close friendship and working relationship with Senior Tribune Nilin. Nilin was always the calmer, more thoughtful one who kept Nauk from letting his emotions get the better of him. He took Nilin's death in the Battle of Three Hills very poorly, entering a rage and attacking the soldier who brought him the casualty listing before being subdued by Catherine.
He also has romantic feelings for Senior Sapper Pickler, putting him in competition with Tribune Robber. Pickler has admitted that though she has little interest in either of them (or anyone else) romantically, she enjoys the reminder they provide that she isn't under the thumbs of the Matrons and could start a relationship without their approval if she wished.