Peottre Blackwater is the kaempra, or war leader, of the Narwhal Clan, and the maternal uncle of Elliania Blackwater.
Peottre is being blackmailed by the Pale Woman, who holds the female leaders of the Narwhal Clan hostage on Aslevjal. Fitz and Chade, who are unaware of the Pale Woman's strength and plotting, often find his behavior puzzling.
Peottre accompanies Elliania to Buck for her betrothal ceremony to Prince Dutiful. Peottre is her mother's brother, and the matriarchal Outislander society accords him greater stature and importance to Elliania than her father Arkon Bloodblade. As a kaempra, or war leader, he speaks with the authority of the Narwhal Clan. He coaches Elliania's speech and behavior, and assists her when her tattoos pain her. He also stands up for Elliania against Henja.
When Dutiful's party arrives in the Out Islands to fulfill his betrothal promise to obtain the head of Icefyre, they are surprised by the strong resistance many of the other Clan kaempras show to their quest. Later, Peottre admits to Dutiful and Chade that he expected such a response, and attempts to extract a promise from them that Dutiful is still bound by his word. He urges them to visit Elliania's motherhouse, which they agree to do. Fitz and Chade are unable to decide whether Peottre's true goal is the marriage pact or the slaying of Icefyre.
While sailing to the Narwhal motherlands on the island of Mayle, an Outislander sailor begins a song about the Black Man of Aslevjal. Peottre brusquely stops the song and keeps the sailor too busy to resume it.