Maeglin was the son of Eöl the Dark Elf and Aredhel, sister of Turgon, and so the nephew of the King of Gondolin. Eöl had taken Aredhel to wife in the forest of Nan Elmoth, against her will, and Maeglin grew up there, dark and fair of face, and with a great skill in mining and in the lore of stones.1
When he was grown, Maeglin went with his mother to Gondolin, against his father's wish, and Eöl followed them and was put to death by Turgon. Maeglin was received as the king's nephew and became one of the great lords of the city. He found rich mines in the mountains around it, and he was proud and reserved, and loved Idril, his cousin.1
Idril would have none of him. After Tuor came and wed her, Maeglin's long envy of them grew into hatred. When he was captured by Orcs outside the city, he was taken to Angband and, to save his life, told Morgoth where Gondolin was and how it could be taken, in return for Idril and the lordship of the city.2
Morgoth let him go back, and Gondolin fell. In the sack, Maeglin seized Idril's son Eärendil on the walls and tried to throw him over. Tuor came on him and threw Maeglin to his death from the ramparts.2
Sources
Citations name the chapter rather than the page, so they work in any edition. The colour of each note shows what kind of source it is.
- Edited posthumously The Silmarillion, Unfinished Tales and Tolkien's late writings on the Elder Days, assembled by Christopher Tolkien from his father's papers.
- Edited posthumously The Silmarillion, Quenta Silmarillion, ch. 16, “Of Maeglin”
- Edited posthumously The Silmarillion, Quenta Silmarillion, ch. 23, “Of Tuor and the Fall of Gondolin”