Grainne administered drugs into the wine of the guests save for Oisín, Oscar, Diarmuid, Caílte and Diorruing. She approached Oisín, who refused her request, then she approached Diarmuid. Diarmuid also objected to her advances because Fionn was a friend and his leader. Grainne imposed a geis on Diarmuid that he must follow her. His friends were saddened, knowing that Diarmuid would die if he came between Fionn and his desired wife. Diarmuid left the palace, knowing that despite being a friend and follower of Fionn, his leader would hunt him down for the betrayal.