Aengus is a member of the Tuatha Dé Danann and associated with youth, love, and poetry. He remains forever at a youthful age and depicted with birds circling his head.
His parents were the Dagda and the river deity, Boann, with whom he had an affair. The Dagda hid Boann’s pregnancy by holding the sun still for nine months so that Aengus was born in one day. When Aengus became of age, he tricked the Dagda of his home by asking his father if he could live in Brú na Bóinne for “a day and a night”. The Dagda agreed, not knowing the Irish have no indefinite article, so “a day and a night” is the same as “day and night”, which comprises all time, and Aengus took custody of Brú na Bóinne forever.
Aengus fell in love with a young woman he saw in his dreams, Caer. He eventually discovered her at the lake of the Dragon’s Mouth, shackled to 150 other girls. On November 1, at the conclusion of Samhain, Caer and the other girls changed into swans for a year, returning to their human form the following Samhain. Infatuated, Aengus was told he could marry Caer if he could identify her in her swan form. He identified Caer. Aengus then turned himself into a swan and they flew away, singing beautiful melodies which put all listeners asleep for three days and nights.
In other tales, Aengus killed a poet for lying about his brother. The poet claimed that Ogma an Cermait was having an affair with one of Lugh’s wives – who was a friend to Aengus. He was also said to heal broken bodies and bring the deceased back to life.