Maegelle was given to the Faith at an unknown age, and eventually became a septa. She was known for her compassion, and her gift for healing. Maegelle played a role in the Second Quarrel, which had begun in 92 AC, when her father, King Jaehaerys, chose Maegelle's brother, Prince Baelon, as his heir over Maegelle's niece, Princess Rhaenys. This decision had angered Queen Alysanne, as she felt there was no reason to favor a man over a woman. It was Maegelle who brought the two back together, solving the Quarrel in 94 AC.
Maegelle nursed children afflicted with greyscale, but became afflicted with greyscale herself and died in 96 AC.