When the Guardians of the Galaxy member Vance Astro changed his own history, and split the worlds of Earth-616 and Earth-691, he unknowingly prevented a major story in Marvel history from happening in his universe. The Secret Wars was pre-empted by the Martian Invasion of Earth. And because of the cosmic event not happening, the Beyonder had no idea about Earth.
1,000 years later, the Beyonder finally got a glimpse of the 691 universe when the madman Bubonicus ripped a hole in Eternity. He was subsequently defeated by the Galactic Guardians and the wound was sealed by the Giraud. 
But the damage was done, the Beyonder had seen into the Earth-691 reality and decided to investigate. During a lovers quarrel between Major Vance Astro and Aleta Ogord, he waited till the latter left, and spoke to Vance, bestowing upon him a costume change. He showed the Major his new playthings, the Protege and Malevolence.
He kept them until Mephisto arrived disguised as The Tracker, and freed them. A fight ensued and both Protege and Beyonder were put on trial for threatening the cosmic order. The trial found him guilty of endangerment and he was sentenced to never view the 691 universe again. Unbeknown to the cosmic beings, he had eyes within through the new suit of Vance Astro.
Powers and Abilities
The Beyonder has any power he wishes to have in any variation at any time. He is the embodiment of his own universe and is an entity not unlike Eternity itself, save for his ignorance of things terrestrial.