Eachtach
In "The Pursuit of Diarmuid and Gráinne" the High King Cormac mac Airt promises the aging Fionn mac Cumhail his daughter Gráinne as a bride , but Gráinne falls in love instead with Diarmuid Ua Duibhne . 
<triplet> Cormac mac Airt <subj> Gráinne <obj> child <triplet> Gráinne <subj> Cormac mac Airt <obj> father