Aarkus and his people came to Earth-616 from another dimension to answer their true calling in life, which was to help Cosmic Cubes all over the Universe gain sentience. Aarkus was assigned to be the caretaker and a midwife of sorts to the Cosmic Cubes of Earth. Aarkus became distracted from his mission when World War II broke out, which he fought in as both a member of The Axis and The Allies.
Mayor Story Arcs
Sometime later; Aarkus was assigned to protect a Cube, that unbeknownst to him, was being corrupted by Humanity's fear and despair. The Cube's corrupting powers began to have a dramatic effect on Aarkus and in the end he changed into the demonic being called D'Spayre, who was thought for Centuries to have been a being created by the Fear Lord known as Dweller in Darkness. Though that could have been just a reality-altering side-effect of Aarkus's transformation, seeing how Dweller in Darkness is responsible for spreading fear and despair throughout the Universe.
Return As Aarkus
When The Invaders were brought to the year 2008 by a Cosmic Cube, but apparently not the one that was corrupting Aarkus, Doctor Strange, The New Avengers, Paul Anselm and a few of The Invaders found D'Spayre hiding with his Cube in an ancient sewer. With Echo‘s help, Doctor Strange took the Cosmic Cube from D'Spayre; purified it and then used its power to banish D'Spayre from existence and by doing so restored Aarkus to his true form. He recently helped reunite the original members of the Invaders.