A former king of medieval northeast Ireland, Suibhne mac Colmain, later known as "Mad Sweeney," was cursed to madness by St. Ronan, a traveling saint scouting grounds to consecrate for a new church. When Suibhne treated their peaceful intentions with aggression, they tried to defuse the situation, only for it to grow progressively worse and one-sided, especially once Suibhne's land was caught up in the Battle of Mag Rath. While Suibhne built an army to participate in the war, Ronan's psalmists attempted to bless his troops with holy water. When they sprinkled him with holy water, Suibhne treated it as an insult and slayed the innocent man, casting his spear through the psalmists' body and killing him instantly.
When he tried to do the same to Ronan, the spear broke against Ronan's bell, leading the saint to pray to God to curse Suibhne to wander the world like a lost bird. Suibhne's wanderings would continue until the day he was slain in the same manner as the innocent psalmist. Unable to abide by human clothes, weapons, or society from that day on, Suibhne was forced to travel the island, sleeping in trees, surviving upon water and plants, and agonized by the cold and his isolation. Each day, he transformed further from the slender, graceful king he used to be, growing talons and feathers and becoming more and more of an animal under Ronan's curse.
Suibhne would wander for years, losing his wife, his kingdom, and his dignity - until he met a pathetic end, lodging in the stable of a parish on the mercy of its priest, drinking filthy water left on the floor by the cook and run through by a stablehand's spear from behind. Despite his madness, though, Suibhne grew to be a respected poet and wiser man due to his travels and suffering. While a brutish lord in life, he died a more noble creature, despite his frenzy.