Leonette Tarly (formerly Leonette Tyrell) is the mother of Garth II Tarly and Bonifer Tarly, and the widow of Quentin Tarly. She is described as a shrewd and capable woman who ruled Horn Hill throughout her son's absence, and continues to rule Horn Hill until her son takes the mantle.
Leonette was the firstborn child to Lord Paramount Luthor Tyrell and Lady Rohanne Florent in 452 AC. She had two younger brothers, Baelor Tyrell and Lyonel Tyrell, both of which are now deceased. As a child, she was betrothed to the then Heir of Horn Hill, Quentin Tarly, as a plan by her grandfather, Lord Paramount Theodore Tyrell, to reunite the Reach after the Westerosi civil war known as the War of the Split Stag.
Leonette learns of the death of her husband Quentin, and her firstborn son, Garth, following the Ascent of the Lion. With her only remaining son, Bonifer, still missing and presumed dead, Leonette assumes the duties of the Lord of Horn Hill.
Bonifer returns home to find his father and older brother have both been slain. He leaves Horn Hill - and later Westeros - in search of recruits to help rebuild House Tarly's forces and win over his mother's approval.
With Bonifer absent once again, Leonette watches her niece Meredyth Tyrell forced to break her betrothal to Bonifer and wed Robert Manderly to cement his claim on Highgarden. With the Tarly forces still in tatters after their defeat in the Ascent, Leonette does not have enough leverage to oppose the match nor the occupation of her old home.
Bonifer writes to Leonette that he has found a new Captain of the Guard for House Tarly, Ser Varus of the Channel.
Bonifer returns to Horn Hill after his adventures around Westeros and Essos with Beren Merryweather, Varus, Tyro and Hycae in tow. Bonifer assumes the lordship from his mother, who remains critical of his inability to lead.
After a fight with Bonifer on his incompetence in his lordly duties, Bonifer leaves Horn Hill suddenly and Leonette is forced to reassume the lordship in his absence. Despite being critical of his ability to lead House Tarly, Leonette worries for his safety.
Horn Hill continues to suffer the effects of famine caused by the blight in the Reach as well as the onset of winter. The food stores within Horn Hill are suffering badly and plans are made to seek assistance from the marcher lords in the Stormlands for assistance. A letter from Starfall arrives, offering a trade deal of food between Dorne the the Reach, which Leonette suspects is a ploy by the Dornish to take advantage of their misfortune and monopolise the Reach's food supply for their personal profit.
Pressure increases on Leonette to find a solution to the famine as discontent with current ration portions rise. Whisperings of a possible smallfolk uprising begin to circulate around the castle.
Matters are further complicated by the murder of the assisting Maester Erryk, who was poisoned in the rookery. The murderer also released all of the ravens from the rookery, essentially disabling Leonette's ability to communicate with the outside world as a blizzard descends on Horn Hill. Leonette then addresses the people of Horn Hill in an effort to rally their support and keep the peace, unknowing that a conspiracy is already quietly underway.
Leonette summons her nephew Olyvar Tyrell to Horn Hill to discuss her agreement to the Dornish trade deal to help ease tensions after a smallfolk riot kills Tarly guards with the food the Dornish would be providing. However, before Lord Tyrell arrives at Horn Hill, Leonette is viciously attacked by a coup to unseat her as Lady of Horn Hill.
"Lady Tarly, a Tyrell in all but name" - Ashara Lannister
"Her look was sharp, yet Olyvar feared her tongue may be sharper if she were to happen upon the Lady Paramount anytime soon." - Olyvar Tyrell