born: 970 at Kambsnes in Hvammsjörður in Iceland
died: 1006 in Sælingsdaltunga in Iceland
married: 1000 Guðrún Ósvífrsdóttir
Bolli's story is told in some detail in the article about Guðrún Óvifrsdóttir. Bolli and Kjartan were raised together as foster-brothers and were inseparable. Kjartan and Guðrún were attracted to one another, and when Kjartan suddenly decided to buy a share of a ship and leave for Norway, he asked Guðrún to wait for him. She refused, not at all pleased with his sudden departure.
Kjartan was detained in Norway, held hostage by the king, but Bolli returned to Iceland. He was not completely honest with Guðrún about Kjartan's fate, and in the end, Guðrún agreed to marry Bolli. When Kjartan returned, Guðrún realized how she had been deceived. She said little, but was clearly displeased. The warmth between Bolli and Kjartan vanished when Kjartan learned of his marriage. Bolli gave him a fabulous gift of stud horses, but Kjartan flatly refused the gift, a stunning rebuke in Viking society.
Then, some of Kjartan's valuables, brought back with him from Norway, disappeared, including a sword. Kjartan accused Bolli of taking the items, which he denied. But Guðrún responded that perhaps they were taken by people who thought that the items were, by rights, their own. Kjartan retaliated by locking Bolli and Guðrún in their house for three days, unable to get out to use their lavatory, which usually was located in out-buildings in the Viking age.
Later, Guðrún learned that Kjartan was traveling nearby with few supporters, the perfect opportunity for an ambush. Early one morning, she woke the men in the house. She incited her brothers and her husband Bolli to attack Kjartan to avenge the dishonor he had showered on them all. She pulled out all the stops, calling into question the men's courage and manliness, saying, "you sit at home pretending to be men."
The men rose and prepared an ambush. They prepared themselves behind a large stone. Anyone riding through the valley would have no clue that men were hiding there, yet a traveler would have to pass close to and below the stone, where the ambushers could easily spring out to attack.
Bolli's reluctance to attack his beloved foster-brother was apparent from the start. He stood on the stone, where he was clearly visible to an approaching rider until the other men pulled him down to the ground by his legs. When Kjartan rode by, all jumped out to attack him, but Bolli stood by passively, his sword Leg-biter in its scabbard. Guðrún's brothers had a difficult time with Kjartan and they called out to him, telling him how shameful it was for him to stand there, unwilling to give them assistance in what was his fight. The saga tells how the fight ended.
At this, Bolli drew the sword Leg-Biter and turned towards Kjartan.
Kjartan then said to him, "An evil deed this is, that you are about to do, kinsman, so much is certain, but I'd rather receive my death at your hands than cause yours."
With that, Kjartan threw down his weapons and refused to defend himself further. He was only slightly injured, although exhausted from fighting. Bolli made no response to Kjartan's words, but dealt him a death blow, then took up his body and held him in his arms when he died. Bolli regretted the deed immediately and declared himself the slayer.
Laxdæla saga, ch. 49
Guðrún was pleased by the news, and Bolli tuned on her in anger at her joy in the death.
Kjartan's brothers wanted to attack Bolli for revenge immediately, but their father would not permit them to go after his beloved foster-son. Instead, he told them to avenge themselves on people who assisted Bolli, which they did. Not until after the death of their father did they attack and kill Bolli.