Lord Paramount of the Trident
From A Wiki of Ice and Fire
After the death of Harren Hoare, the King of the Isles and the Rivers, at Harrenhal during the War of Conquest, Aegon the Conqueror granted the riverlands to Lord Edmyn Tully of Riverrun and named him Lord Paramount of the Trident.
A Clash of Kings
After the assassination of King Renly Baratheon, Petyr and Tyrion Lannister plot to form an alliance with House Tyrell to win over any lords from the Reach or the stormlands that did not immediately declare for King Stannis Baratheon. Petyr volunteers to travel to Bitterbridge to broker the deal, and is successful in forging a Lannister-Tyrell alliance through the engagement of King Joffrey Baratheon and Margaery Tyrell. He returns to King's Landing with Tyrell forces alongside those of Lord Tywin Lannister. The allied Lannister and Tyrell armies are able to take Stannis's forces in the rear in the last hours of the Battle of the Blackwater, with Petyr providing the idea to dress Garlan Tyrell in King Renly's armor during the battle so as to frighten Stannis's men-at-arms.
After the battle, Petyr is rewarded with the title Lord Paramount of the Trident and is made the liege lord over the riverlands, as House Tully has sided with Robb Stark, the King of the Trident, instead of the Iron Throne. Petyr is also made Lord of Harrenhal, although it is still held by Lord Roose Bolton in Robb's name. Though Petyr has not set foot in the castle, the title gives him nominal control over the war-torn Riverlands and elevates his rank considerably.
|“||It is the wish of the King's Grace that his loyal councillor Petyr Baelish be rewarded for faithful service to crown and realm. Be it known that Lord Baelish is granted the castle of Harrenhal with all its attendant lands and incomes, there to make his seat and rule henceforth as Lord Paramount of the Trident. Petyr Baelish and his sons and grandsons shall hold and enjoy these honors until the end of time, and all the lords of the Trident shall do him homage as their rightful liege.||”|
|“||Lord Paramount of the Trident, Sansa thought, and Lord of Harrenhal as well. She did not understand why that should make him so happy; the honors were as empty as the title granted to Hallyne the Pyromancer.||”|