After the devastation of the Children of Danu by the Milesians, they gathered together to choose a new king. The Dagda, who ruled before declared himself unfit to rule them because he did not prevent their downfall. So they chose Bodb Dearg, son of the Dagda. Lir, the God of the ocean became angry and jealous believing he should have been chosen. He left the assembly and refused to talk to anyone or pay homage to Bodb Dearg.
Lir’s wife, mother of Manannán Mac Lir, died and Lir became lonely and bitter. After a period of mourning, Bodb Dearg held out the hand of friendship to Lir. If Lir accepted him as king of the Children of Danu he would arrange a marriage with one of his three beautiful foster daughters Niamh, Aoife or Aobh. Lir was delighted, having grown weary of his isolation and feasted with the Children of Danu for several days before meeting the foster daughters.
Lir took Aobh in marriage and formed an alliance. Aobh and Lir had four children; one girl, Fionnghuala, and three sons, Aodh and twins, Fiachra and Conn. After the birth of the twins Aobh died, causing more grief to Lir. Lir then married Aoife, who became jealous of Lir’s affection for her four step children. She feigned illness for around a year before setting out in her chariot with the children, planning to kill them, and called her servants to slay them, promising them rich rewards. They refused, so she drew a sword, but was unable to follow through. So she took them to Loch Dairbhreach, and whilst they bathed she cast a spell to transform them into four white swans.
She set a period of three hundred years as swan on Loch Dairbhreach, three hundred more on Sruth na Maoilé and three hundred at Iorrus Domnann and Inis Gluairé. She also foretold that at the end of the period King Lairgenn and Deoch would be wed. Aoife did relent a little and allowed the children to retain the power of speech, allowing them to sing songs without equal to stop their distress by being in the forms of swans. When Aoife returned to court, Bodb was suspicious after enquiring about the girls and sent messengers to Lir.
Lir realised Aoife had done some harmful act and found the children on the shores of Loch Dairbhreach signing with human voices. They told him of Aoife's evil act, and Lir and his people lamented and stayed with them. Bodb cursed Aoife and struck her with a druid's wand, changing her into a demon of the air, known as the Mórrígan. By the end of nine hundred years, the children became human again when King Lairgenn put the swans in his boat as a gift to his bride. However, they aged rapidly and when they died were graciously buried in a sacred place.