Gerold was born and raised in the Reach. He had a complicated relationship with his father, due to Gylen's apparent madness.
After the War of the Ascent of the Lion, Gerold was married to the newly widowed Ashara Lannister. The young couple was well liked by the people of Oldtown, and the subject of much gossip.
In the third era, Gerold was sent by his father to Highgarden to retrieve Mellara Tyrell after the death of Robert Manderly. She was taken back to the Hightower as a ward, though it was later revealed that she was being kept prisoner and subject to torture from her capture until the time of her death.
During the War of the False King, Gerold leads a small army to New Barrel in order to investigate recent acts of aggression against the holdings, which the Dornish were behind, and burn large tracks of the Roseroad to make King Damon's passage more difficult. While returning after a stay at Horn Hill, his army was set upon by Damon's and the majority was captured, including Lord Marq Beesbury. Gerold himself managed to escape with a retinue of eight knights.
When he arrived back at the Hightower, he learned that Ashara was with child and Damon's army was approaching the gates. After his father was killed by Queen Danae Targaryen and her dragon Persion, King Damon bestowed all of the titles that would have been his on Ashara Lannister, sparing Gerold from a sentencing to the Wall only at Ashara's insistence.
Ashara gave birth to their son, Loras Hightower, in the fifth era. Gerold, in the midst of the worst mid-life crisis in family history, fled in the night shortly after Loras was born. He would spend years in hiding just a few days travel from Oldtown.
Gerold finally made the decision to return to his home after years of wrestling with the decision. He was not greeted especially warmly as many of the house staff had been replaced by Ashara's people. Still, he decided to take a pro-active role in the governance of the Reach and despite his lack of political power has managed to keep a seat on Ashara's council. Though his insights are often ignored or disparaged for their seeming childishness, Ashara continues to hear Gerold's take on any subject in question.
"Gerold had never doubted his own appearance, and as the vain, Reach-born boy he was, he felt just a little more confident knowing how homely his political opponents were." - Blood and Whispers
“Gerold is bitter. He drinks himself silly from sunrise to sunset and has grown petty to the point where he refuses to even dine with me at the same table.” They had loved each other once, or so she thought. Back when knights in shining armor used to sweep me off my feet, and I fell head over heels for Gerold’s asinine letters and boyish smile. - Ashara Lannister
Gerold had been all but giddy after the war, relieved to be freed from the yoke that was Gylen’s appraising eyes and unpredictable whims, no longer needing to worry about the bore that was ruling a kingdom, happy to pass the burden onto his wife while he carried on doing whatever it was that he wanted - usually sparring in the tiltyards, hawking, or feasting. But the day that brought their son also took away her husband. He began to brood whenever she left him to tend to the child. Then his acrimony began to pour over into public, where he began contradicting her when she held court, showing up drunk to feasts she held to inspire goodwill toward the Crown in the Reach. It took becoming a father himself for Gerold realize exactly what he had lost, and every time he looked into Ashara’s eyes - the same hue as his son’s, the same color as the man who was ultimately responsible blotting his birthright - the wound bled once more. - Blood and Whispers
Gylen Hightower, father (deceased)
Ashara Lannister, wife
Loras Hightower, son