Through the King Zeus, Leto is the mother of Apollo and Artemis. When she was pregnant with the twins, she was pursued relentlessly by the goddess Hera, who drove her from land to land preventing her from finding a place to rest and give birth. The floating island of Delos eventually provided her with refuge. Later when she was later traveling to Delphi, the giant Tityos attempted to abduct her, but Apollo intervened and slew him with arrows.
Latona is Leto's Roman counterpart. As Latona, she becomes more disciplined, warlike, and militaristic. In Roman mythology, she is the Titaness of motherhood and modesty.
Her son Apollo mentions her frequently throughout the book. He also recalls that she used to call him 'a special snowflake'.
After Apollo drinks from the two springs of memory and forgetfulness to prepare for his trip into the cave of the Dark Oracle, he begins hallucinating, and one of his visions is of Leto kneeling and pleading with Zeus to end Apollo's punishment and allow him to return to Olympus. However, Zeus refuses, saying that his real test is yet to come.