Piter is Baron Harkonnen’s Mentat. Cunning and cold, Piter is suggested to be a particularly intelligent Mentat, as he was able to find a way to override Yueh’s Imperial Conditioning – which was considered to be foolproof – and convince him to aid in the assassination of the Duke Leto. Piter and Baron Harkonnen have a complicated alliance.  Piter enjoys the power that his role as the Harkonnen’s Mentat provides him, but his intelligence and ambition make him the rightful target of the Baron’s distrust. Both men continually intimidate each other with displays of power, with the Baron frequently threatening to have Piter assassinated. Piter takes these threats seriously, but doesn’t expect immediate retaliation from the Baron, as he knows that he is a valuable presence in House Harkonnen. It seems that Piter likely has his own personal ambitions and plans, and that he advises the Baron in a way that is also advantageous for his personal interests, but he never reveals what these might be.

Despite his intelligence and effectiveness, when Piter is killed by the Duke Leto’s poison tooth, it becomes clear how replaceable he was in the eyes of the Harkonnens. While the Baron is initially annoyed by Piter’s death, he quickly replaces him with Thufir Hawat. The Harkonnens see Mentats as tools, not as human beings, which contrasts with how House Atreides saw their Mentat as a vital member of the household.