Kymil was a member of the Nimesin clan, which was a minor branch of the Durothil clan, one of the oldest and most honored houses. He loved Filaura Ni'Tessine, one of his Elite Guard and Circle Singers but she was killed by Arilyn
Kymil was over 600 years old by 1369 DR and had borne witness to the fall of Myth Drannor and the rise of the House Moonflower rulers of Evermeet. The latter event he regarded as an abomination that never should have happened, considering the sun elves to be the true rulers of elvenkind. He had spent much of his life toiling endlessly to come up with a plan to kill off the royal family of Evermeet and restore the Council of Elders, which was the form of government in the days of Myth Drannor. Towards this end, he employed numerous agents and resources, including a group of gold elves he referred to as his Elite Guard, treasure taken from a dragon's hoard and even the dark elven goddess Lolth.
His efforts had almost succeeded, and all members of the royal family but three were dead, including King Zaor Moonflower and Princess Amnestria, the mother of Arilyn Moonblade. However, Arilyn and Danilo Thann managed to relocate the portal to Evermeet he planned to use, and she defeated him in hand-to-hand combat. He was tried by a Harper tribunal and sentenced to lifelong imprisonment in some remote dimensional plane, but escaped with the aid of Lolth and renewed his plan by mounting a massive assault upon Evermeet that left many elves dead. He was again stopped, this time by Prince Lamruil, but again escaped through use of a magical ring.
Kymil's whereabouts afterwards were unknown, but he was believed to be pursuing the same goal, which he had come to believe in so fanatically that there were many who questioned his sanity.