A warrior of the Fianna whose flight with Fionn's intended bride, Gráinne, becomes one of Irish mythology's great tragic love stories.
Diarmuid Ua Duibhne is a warrior of the Fianna, foster son of the god Aengus, and famed for a "ball seirce" (love spot) on his forehead — hidden beneath his hair — that makes any woman who sees it fall instantly in love with him. He otherwise keeps it carefully concealed, aware of the chaos it causes.
The central story of his life begins at the wedding feast of the aging Fionn mac Cumhaill to Gráinne, daughter of the High King Cormac mac Airt. Gráinne, unwilling to marry a man so much older than herself, places the assembled company under a binding magical geis (an obligation that cannot be refused) to help her elope instead with a younger warrior of her choosing — Diarmuid. Bound by the geis and by his own sense of loyalty to Fionn despite his reluctance, Diarmuid ultimately flees with her, beginning a pursuit across Ireland that occupies a large portion of the wider Fenian material, with Fionn and the Fianna in relentless chase and the god Aengus repeatedly intervening to protect his foster son from capture.
Diarmuid and Gráinne eventually settle and live together for years, and Fionn's anger cools enough that an uneasy peace is made between them. Diarmuid's death comes later and separately from the elopement story, during a boar hunt on Ben Bulben: gored by a magically poisonous boar he was fated to fight, he lies dying, and only water drunk from Fionn's own hands has the power to heal him. Fionn, still carrying old resentment, delays — letting the water slip through his fingers twice before finally moving to save him — and arrives too late. The story stands as one of Irish mythology's most enduring tragic romances, and Diarmuid and Gráinne's flight is traditionally said to be commemorated across Ireland in the many megalithic portal tombs still popularly called "Diarmuid and Gráinne's beds."
Tales of Fionn mac Cumhaill and his band of warriors, the Fianna, set generations after the Ulster Cycle in a world of hunting, romance, and roaming adventure.
Diarmuid Ua Duibhne is a warrior of the Fianna best known for the "love spot" on his forehead that makes any woman who sees it fall for him, and for his role in eloping with Gráinne, the betrothed of his own leader, Fionn mac Cumhaill.
Why did Diarmuid elope with Gráinne?
Gráinne, unwilling to marry the much older Fionn, placed Diarmuid under a binding geas (taboo obligation) to take her away instead — a compulsion he couldn't honorably refuse, even though it meant betraying his loyalty to Fionn.
How does Diarmuid die?
Fionn, still resentful years later, withholds the one thing that could save Diarmuid after he's gored by an enchanted boar — water carried in Fionn's hands, which could heal him — letting it slip through his fingers until it's too late.