When Ser Gregor Clegane "the Mountain that Rides" begins raiding the Riverlands Ned Stark sends a hundred men under Beric to arrest the Mountain. As Beric's squire Edric accompanies him. However they are ambushed at the Mummer's Ford and Beric is wounded by the Mountain's lance. Edric Dayne pulls him from the water and stands over him while the fighting happens, though Beric dies. The Red Priest Thoros of Myr, who was in the party and is a friend of Beric, performs the last kiss on Beric, a rite of R'hllorism. To his astonishment Beric is brought back to life. He rallies the survivors to fight the Lannisters' invasion of the Riverlands. However when King Robert dies the Lannisters usurp the throne, making Beric and his men outlaws. Eddard Stark is executed by the Lannisters' King Joffrey Baratheon. Eddard's son Robb Stark arrives in the Riverlands to fight the Lannisters, and on hearing of his father's death the Northmen and Rivermen at Riverrun proclaim him King in the North.
The war between the Lannisters and Starks leaves the Riverlands in ruins. Beric raids the Lannisters' foraging parties. Though some of his men die, others join Beric's force, who become the Brotherhood without Banners. Edric continues to squire for Beric. Though Beric and his men were originally sent to fight the Lannisters, the Brotherhood fights all who oppress the smallfolk. Stories develop about Beric, claiming he can't be killed, as several men claim to have killed him but he keeps returning.
Beric is killed five times, and each time Thoros revives him. Beric meets Arya Stark, the younger daughter of Ned Stark, and Gendry, a bastard of Robert Baratheon. They are brought to the Hollow Hill, the base of the Brotherhood. The Brotherhood capture Gregor Clegane's brother Sandor Clegane, "the Hound" and Beric has a trial by combat with him. Ned helps armor Beric for the battle. The Hound kills Beric, but Thoros revives him for the sixth time.
Later the Brotherhood encounter a group of the Brave Companions, a vile sellsword company also known as the Bloody Mummers, at a burning Septry and fights them. Edric takes part in the battle, by which time he's 12. He befriends Arya and claims that he and her half-brother Jon Snow are milk-brothers. His mother didn't have enough milk for him so he was nursed by a woman called Wylla who was in service at Starfall. He claims Wylla is Jon's mother. Ned also tells her the story of his aunt Ashara Dayne throwing herself into the sea before he was born as her heart was broken by Eddard, who she loved. Arya gallops away upset, saying Ned's a stupid liar to Anguy. Harwin, a former guardsman of Winterfell, says he has heard the story as well but it happened when Arya's mother Catelyn was betrothed to Ned's elder brother Brandon Stark. Harwin asks her not to mention this story to her mother.
In what becomes known as the Red Wedding, Robb Stark, his mother Catelyn Stark, and most of their army are massacred and Catelyn's brother Edmure Tully captured by their treacherous vassals, the Freys and Boltons, who have secretly joined the Lannisters. Catelyn is stripped and thrown in the river after a day and a night. Arya, while warging into her direwolf Nymeria, finds her mother and drags her out of the water. She is found by the Brotherhood and Harwin, a former guardsman of Winterfell, begs Thoros to bring her back. However Thoros claims she has been dead too long. Beric then performs the last kiss on her, and Catelyn rises, while Beric dies a seventh and final time. Leadership of the Brotherhood is taken by Catelyn, who becomes known as Lady Stoneheart. Stoneheart's mission, to take vengeance on all those she believes connected to the Lannisters, leads the outlaw band to fracture. Edric is among those who leave.