Maeve Goddess-Queen a powerful wild warrior deity sponsored and destroyed heroes. No king can rule Ireland unless he has engaged in the Sacred Rite with Maeve and satisfied her. Maeve takes mortal kings as her consorts contracting them in sacred marriage giving them their right to rule and bestowing prosperity on the land but only as long as she perceives them fit to rule. (Or until she finds someone more fit.) Maeve makes kings and breaks them too. She can deprive men of their strength merely by being in their presence.
Irish myth describes how Maeve manifested to Niall of the Nine Hostages as an old crone guarding a well. She gave him water and he agreed to have sex with her. In his arms she transformed into a young gorgeous woman and granted him kingship of Ireland. Fergus is her first husband. She abandoned the second Conchobar once she perceived him unworthy to be king. She has several criteria for choosing her third: his courage fearlessness and generosity must match hers and he must not be jealous - this is crucial as she must engage in sacred marriages. Of course when he's unfaithful she kills him.
Irish myths were transmitted orally. The first to write them down were Christian monks who sought to preserve them but clearly disapproved of Maeve's rampant sexuality. They did not represent her as a grand Pagan goddess but as a lustful violent warrior woman the archetypal fairytale evil queen.
Maeve was not forgotten or relegated to storybooks. Too powerful to suppress post-Christianity she emerged as a fairy queen. In Ireland she remained full-size but in England and Wales fierce warrior goddess Maeve under the name Queen Mab is reduced to a flower fairy a tiny miniature spirit who rides a chariot pulled by insects.