The hedonistic former Institute Proctor, now Darrow's ally and covert emissary in the Mars war.
Proctor Jupiter, the arrogant, hedonistic Gold who oversaw Jupiter House at Darrow's Institute, resurfaces on the eve of the Mars invasion as an ally—an ambling, pitiless beast of a man half a foot taller than Darrow, forever two misunderstandings from a duel with Ragnar. Bested by Fitchner in the duel for the Rage Knight's seat (sliced 'the same place Sevro did'), he has spent weeks as Mustang's emissary, slipping in and out of the communication-interdicted loyalist cities to coordinate the war her agents and the Jackal's have waged on Mars. He approves of Darrow's new razor fashion, reports that Imperator Tiberius au Bellona commands the Bellona fleet while Cassius and Karnus run ground operations in Agea, and volunteers to help hunt and kill the Bellona—the surest way to make their allies quit the fight.
A tall, hedonistic Gold, half a foot taller than Darrow, hair bound tight, careless in the eyes, arrogant and beastly; wears his razor in the new arm-coiled fashion.
Former Institute Proctor turned Darrow's ally; covert emissary and Bellona-hunter.
Also appears in books you've already read — spoiler-safe to their endings: