Brida is Uhtred's friend and later lover. Like Uhtred, she is Saxon in origin, and is adopted by the Danes after they see the ruins of her village, wiped out by a raiding party from a rival band of Vikings and experience Brida's feisty nature. Also like Uhtred, she comes to love the Danes for their free-spirited nature. She and Uhtred become playmates and close friends. When they reach adolescence, they become lovers. Brida becomes pregnant by Uhtred but miscarries.
She was my age, black haired, thin as a twig, with big dark eyes and a spirit as wild as a hawk in spring, and she was among the captured women [...] Brida stayed close to me. Ragnar had taken a strong liking to her, probably because she treated him defiantly and because she alone did not weep when she was captured. She was an orphan and had been living in the house of her aunt, the woman whom she had beaten and whom she hated, and within days Brida was happier among the Danes than she had ever been among her own people. [...] Brida was learning quickly. She had a mind like a fox, quick and sly.
Along with Uhtred, she learns the art of making charcoal for forging steel, and so survives along with Uhtred when Ragnar and the others are killed in the night-time attack by Kjartan The Cruel. Brida despises the straight-laced, pious Christian Saxons of Alfred's court even more than Uhtred does. When they both have the opportunity to join Ragnar the Younger, Uhtred decides to return to Alfred to complete his oath-sworn service, and she does stays with the Danes, later becoming lovers with Ragnar the Younger - now known as Ragnar Ragnarson at the time of the events. As of The Burning Land Brida hates Uhtred for abandoning the fight against Wessex with Ragnar.
I did fear Brida. She had been my lover once, and now she was my enemy, and a grudge, for Brida, was like an itch that never went away. She would scratch the itch until it became a sore, and gouge the sore to suppurating blood and pus. She hated me because I had not fought for the Danes against the Saxons and it did not matter that she was a Saxon herself.