Gráinne

Gráinne is promised in marriage to Fionn mac Cumhaill, leader of the Fianna, but at the betrothal feast she instead binds Diarmuid Ua Duibhne to elope with her under a geis — a ritual obligation he cannot honorably refuse, however reluctant he is to betray his own leader.

The two are pursued across Ireland by Fionn and the Fianna for years, a chase so extensive it gave its name to numerous "Bed of Diarmuid and Gráinne" megalithic sites across the country in later folklore. Fionn eventually reconciles with the couple, at least outwardly — but when Diarmuid is later fatally gored by an enchanted boar, Fionn deliberately lets a cure that could save him slip through his fingers, letting old jealousy settle the score.