Alpheus Benthos

Alpheus Benthos is the primary antagonist of Season 2. He commands a nuclear-powered submarine of his own design, which he claims to be the fastest sub around. The sub is controlled by an AI named A.R.I.A. (Augmented Response Intelligent Application), who he is very attached to as shown in "Just Eaten".

Alpheus is the self-proclaimed "nemesis" of Antaeus Nekton, who believes their fates are intertwined. He seeks the secrets of Lemuria, so he can awaken a mysterious doomsday weapon called "The Terror", working alongside Proteus to do so.

Alpheus's suit is embedded with electronics that allow him to shoot disabling rays right from his forearms.

Proteus
After being banished from the Guardians, Proteus ends up working with Alpheus in their discovery for Lemuria.Proteus is last seen in the season 2 episode, "Hidden secrets".

Nekton family
Antaeus Nekton sees Alpheus as an "arch enemy" despite a claim by the Nekton family that they are a relative to Alpheus. Despite this, Alpheus made attempts to steal the Ephemychron from the Nektons to achieve their promise. Despite this, there has never been a single attempt from Alpheus using the Ephemychron for the use of navigation as the Nektons had used it.

Trivia

 * Alpheus mentions to the Nektons that he will never see them again in the season 3 episode, "Just Eaten". After the events during that episode, he is never seen again.
 * Alpheus is descended from a different branch of the royal line of Lemuria than the Nektons, the rogue branch.