When Fëanor spoke in Tirion, Aegnor was moved by his words, as well as his brother. but neither spoke against their father. Later, he and his brothers followed the host of the Ñoldor to Middle-earth and held the northern slopes of the highlands of Dorthonion against Morgoth throughout the time of the Siege of Angband.
He later fell in love with the Bëorian woman Andreth Saelind, and she returned his feelings. They spent much time discussing Men and Elves and their fates in the world, which are fully explained in the Athrabeth Finrod ah Andreth. However, they were both killed soon after when Morgoth broke the Siege at the start of Battle of Sudden Flame in 455 1A.