Aeglin is Teleri. He was born in the first age and trained as a shipwright and mariner. Somehow, he managed to avoid most of the trouble with Feanor, although he had some boats stolen.
During the Second Age he worked ferrying Elves between Valinor and Numenor, until the Numenorians attempted to follow and thus had their island sunk. In the Third Age he moved to the Grey Havens and worked as a shipwright with Cirdan building ships for all the Elves leaving Middle-Earth
Now he doesn't have much of anything to do.
....I'm such a nerd.