Born in Lindon during Gil-Galad's rule. His mother was a warrior who lost her life in the Battle of the Last Alliance. His father was a blacksmith who did much of the childrearing. Gelluingil was raised with a great affinity with swords - both their use and their creation. He had always been an inquisitive mind, and was forever asking questions. One of these was regarding where his father had learned to make swords, leading to a desire for an understanding of the history of the elves' relationships with crafting, and their history with one another and with the other free peoples. He always had an interest in the social aspects of history, and over time, he began to focus upon it, a great desire for knowledge of the various races and factions and their cultures.

During this search for knowledge, Gelluingil became devoted to the idea of deep collaboration and cooperation, both militarily and culturally. As such, he moved to Imladris to work on becoming a diplomat for Elrond.