Beric Dondarrion is the Lord of Blackhaven and the head of House Dondarrion. Initially sent out by Eddard Stark to lead a party of men to apprehend Ser Gregor Clegane for atrocities committed against the people of the Riverlands, Dondarrion became leader of the outlaw resistance group known as the Brotherhood Without Banners.
Beric Dondarrion is the Lord of Blackhaven and the head of House Dondarrion, a vassal house to House Baratheon of Storm's End. He is a young lord who still enjoys the life of a knight, including taking part in tourneys. He is visiting King's Landing when the series begins.
Upon hearing of the atrocities committed by Ser Gregor Clegane, Lord Eddard Stark, acting as the Hand of the King, orders Lord Beric to take a hundred men, ride to Ser Gregor's keep and execute him for treason and murder. Beric willingly agrees to the task.
Lord Beric is rumored to have been killed in the Battle at the Mummer's Ford. The survivors form the Brotherhood Without Banners. In fact, Beric is actually killed by the Mountain, who drives a lance through his chest. Thoros of Myr unwittingly resurrects him.
Dondarrion reunites with Thoros' party at Hollow Hill, the headquarters of the Brotherhood Without Banners, and is surprised to see they have captured Sandor Clegane. Beric reveals he has converted to the religion of the Lord of Light. After Arya Stark accuses the Hound of murder, Beric sentences him to trial by combat as there is no other witness to confirm his guilt, and chooses himself as Clegane's rival.
Using magic, Beric ignites his blade with fire, initially giving him an advantage during the fight due to Sandor's fear of fire. However, Sandor's superior strength eventually proves enough to overpower Beric, and with a powerful downward swipe Sandor cuts deep into Beric shoulder, nearly cutting off his entire arm and cutting right through his flaming sword. Arya attempts to kill the Hound while he tries to extinguish his shield which had been set a flame during the fight, but she is stopped by Gendry. Sandor taunts Arya over how the gods prefer him over her friend, but he is interrupted and shocked by Beric, who has been revived and healed by Thoros using the Lord of Light's power. Since Sandor effectively won the fight, Beric declares him innocent and sets him free, but keeps Arya with the Brotherhood, intending to ransom her to her mother and brother at Riverrun.
Later, Beric reminisces on the times he has been killed with Thoros and Arya. Arya briefly asks if Thoros can revive a man with no head, clearly referring to her father, but Beric merely compliments Eddard's honourable nature and tells her of the side effect of his resurrection: with each revival, he loses some of his memories and is less himself, a life he would not wish on Eddard. The group is later encountered by Melisandre, who seeks out Gendry. Melisandre briefly examines Beric and is clearly astonished at how Thoros has been able to revive him so many times. Against Arya's wishes, Beric sells Gendry to Melisandre for gold, a decision that later leads Arya to abandon them. When Beric informs Arya that they will be delaying ransoming her in order to launch an attack on some Lannister soldiers instead, it is the final straw and Arya flees from the group.
Remembering how Beric was revived by Thoros six times, Melisandre attempts a ritual to resurrect Jon Snow following his murder, which is successful.
Beric prepares to hang Lem and two other members for raiding a community that was building a sept, staining the good name of the Brotherhood. However, Sandor Clegane, who had become a member of the community, hunts down Lem and demands he be allowed to kill the man himself, as vengeance for the hanging of Brother Ray. After some arguing, Beric and Thoros allow the Hound to hang two of the men himself, out of respect for the loss of his friend, but refused to allow him to kill them in a barbaric manner. Beric personally hangs the third man. Later on, Beric offers Sandor a place in the Brotherhood, as he needs good men. He says there are "cold winds" rising in the North, and he intends to stop them.
The Brotherhood Without Banners travel through thick snow. They decide to shelter for the night at an abandoned village but Sandor thinks it is unsafe. Beric Dondarrion dismisses Sandor's unease and orders that they set up camp for the night. The men enter a hunt where they discover the corpses of the Farmer and his daughter Sally, Sandor and Arya Stark had encountered two years prior, following the Red Wedding. It appears that the father killed his daughter and himself so that they would not starve to death.
In private, Sandor recalls seeing Beric at the tournament at King's Landing. Beric confides that he does not know what R'hllor, the Lord of Light, is telling him. Sandor remarks that he does not believe in divine justice, citing the fate of the father and his daughter and that Beric should be dead in their places.
While making their way north, Beric, Sandor and Thoros are captured by Tormund and the wildlings manning Eastwatch-by-the-Sea south of the Wall. The three are brought to Eastwatch where they are incarcerated in the ice cells until they are accosted by Jon Snow, along with Jorah Mormont and Gendry. Despite initial distrust, particularly on Gendry's part, since Beric and Thoros sold him to Melisandre, Jon decides that they are on the same side, and he releases them. Beric, Thoros and Sandor join Jon, Gendry, Jorah and Tormund on their quest north of the Wall to help Jon capture a wight to bring to Cersei Lannister.
While travelling beyond the Wall, Beric and Jon have a conversation. Beric claims that Jon does not look much like his father, which takes Jon by surprise. Beric reveals that it was Eddard Stark who sent him and Thoros to hunt the Mountain. Revealing that he heard from Tormund that Melisandre brought Jon back from the dead, Beric tells Jon that Thoros brought him back six times by now. Beric claims that both of them serve the Lord of Light. Jon replies that he serves the North and that the Lord of Light never spoke to him. When Jon claims that he does not know what the Lord of Light wants of him, Beric replies that the Lord wants both of them alive so that they can fight for life itself. Beric states that death is the enemy and that, although the enemy always wins, they still need to fight him.
When a snowstorm sets in, the group is suddenly ambushed by a wight polar bear. Beric and Throros ignite their swords to fend off the undead beast and although the team is able to defeat the beast in combined effort, Thoros is mauled and gravely wounded by the bear. After the bear has been destroyed, Beric stops Thoros' bleeding by cauterising the wound with his flaming sword.
Further north, the group eventually encounters a White Walker accompanied by a small group of Wights. The team ambushes the Walker and the wights and after Jon kills the Walker, all but one wight smash to the ground motionless. The team captures the wight but they are soon forced to flee when the full force of the undead army comes down onto them. They flee to an island on top of a frozen lake, which grants them temporary safety as the wights break through the ice and are unable to cross. Surrounded by wights, the group is forced to wait out the night in the cold. As Jon has sent Gendry back to Eastwatch to send a letter to Daenerys Targaryen, Daenerys is the group's last hope to flee the North alive. An entire night passes and the next morning, the group realizes that Thoros has frozen to death. Mourning his deceased friend, Beric says a prayer for Thoros before he ignites his corpse with his sword so that he cannot reanimate as a wight.
After burning Thoros, Beric joins Jorah and Jon who are discussing that Daenerys is their only hope. Beric claims that there is another and points at the Night King, who is watching the trapped group from a nearby hill. Beric states that the Night King is the one who turned them all and thus, killing the Night King would annihilate the army of the dead in one swift stroke. Beric tells Jon that this might be the purpose the Lord of Light has for them, as he hardly brought them back only to watch them freeze. Sandor then chips in, reminding Beric that he lost his priest and is thus on his "last life".
Eventually, the water freezes again and the wights advance onto the island. The group prepares for their last stand and Beric once more ignites his sword, killing many wights. When it comes to battle, the sheer masses of the advancing undead force the group further back onto the island. When all hope seems lost, Daenerys suddenly sweeps in with her three dragons Drogon, Viserion and Rhaegal. While the younger two dragons annihilate the advancing undead, Daenerys lands Drogon on the island so that the men can climb up onto the dragon. All but Jon, who is still fending off wights, make it onto the dragon where they witness the Night King hurling an ice spear at the flying Viserion, impaling him through the neck and causing the dying dragon to fall onto the ground, break through the ice and sink to the ground of the lake. All onboard the dragon, Beric included, watch in awe and horror. As the Night King is already preparing another projectile, Drogon is forced to set off and the group, except for Jon, fly back to the Wall.
Having returned to Eastwatch safely, Beric, Tormund and Sandor deliver the wight. After having hurled the wight into the boat, Beric and Sandor split up as their travel together has come to an end. Beric claims that they will meet again, to which Sandor replies that he "fucking hope[s] not".
While most of the group make their way down south to meet Queen Cersei, Beric remains at Eastwatch together with Tormund and his wildlings. While both men stand on top of the Wall facing north, they suddenly witness the arrival of the White Walkers and the army of the dead. While they are watching in awe, the Night King suddenly comes swooping in on top of the reanimated Viserion. Viserion blasts blue fire at the wall, causing outer shells to crack off. Tormund and Beric immediately realize the situation and, together with most of the other men on top of the Wall, immediately abandon their position and run off. While Beric and Tormund run west on top of the Wall and eventually reach a zone unaffected by Viserion's fire, Viserion continuously breathes fire onto the Wall, eventually bringing down a large part of it and allowing the dead to enter the Seven Kingdoms.
Lord of Blackhaven, Beric Dondarrion arrived in King’s Landing to compete in the Tournament of the Hand given in honor of Ned Stark, then Hand of the King. After Gregor Clegane terrorized the Riverlands, Lord Beric was tasked by Ned to bring him justice. A follower of the Lord of Light, Beric has been brought back to life several times by a Red Priest, Thoros of Myr. After hanging the men who raided Brother Ray’s community, he offered Sandor “The Hound” Clegane to travel north with the Brotherhood. The group now plans to help Jon Snow beyond the Wall.