Lieumon

Lieumon is a Slash ship between Amon and the Lieutenant in The Legend of Korra series.

Canon
It is unknown how Amon first met the Lieutenant but they worked closely together as Equalists. The two always had mutual trust and admiration for each other. Amon trusted the Lieutenant enough to make him is second in command and the Lieutenant dedicated his life to Amon and his cause. Both believed in ridding the world of all bending. The Lieutenant always accompanied Amon in public appearances and in fights. Eventually, Korra revealed that Amon is actually a waterbender named Noatak but the Lieutenant did not believe her. However, he later witnessed Amon bloodbending Korra. He was hurt by this because of his dedication to Amon and charged at him which prompted Amon to bloodbend him aside while remarking that he had served him well. Amon was later killed in a boat explosion by his brother Tarrlok. It is unknown what happened to the Lieutenant.

Fanon
Lieumon is a highly popular ship in the Legend of Korra fandom and is one of the most popular slash ships. It had a decent amount of shippers from the start and increasingly became more popular as Book One: Air was airing. It especially became popular when the Lieutenant was hurt by the revelation of Amon's true identity and remarked that he dedicated his life to Amon. Many fans pointed out that the specifically said that he dedicated his life to Amon and not his cause or the Equalists. A lot of fan fiction about them has been written despite the fact that Amon is dead.