Origin

In the mainstream time line after escaping confinement from his mother Moira MacTaggert, Proteus battled Phoenix, Madrox, the Multiple Man, and Polaris. Polaris and Multiple Man were easily defeated but he the Phoenix nearly killed him. After taking control of his father's body he was confronted by the X-Men. He completely burned out his father's body, destroying it. Before he was able to inhabit a new body Colossuspunched him which dispersed his energy around the entire world because his energy form is weak against metal.

Powers

Proteus can generate enormous amounts of psychic force from his energy state that allows him to restructure reality in any manner. He exists as an energy form that can inhabit human bodies to contain his energies, however any body he possesses quickly begins to break down so he constantly needs new host bodies.

Alternate Realities

Earth-1610

In the Ultimate Universe he is the son of Moira Mactaggert and Professor X and his name is David Xavier. As he grew up he enjoyed sports and video games and was unable to relate to his intellectual father; because of this he felt that Charles disliked him. Charles left with Magnetoto form the Brotherhood Of Evil Mutants and left David disliking him even more. The next day his powers began to manifest. He left to search for his father inhabiting bodies of anyone he saw and going to a new one as the host body's energies wore out. He was eventually confronted by the X-men and his parents and he took control of Wolverinebody knowing that Wolverine's healing factor would counteract David's energy drain. Just before getting hit by a truck he left Wolverine's body and eventually found his way to the body of Betsy Braddock, or Psylocke. He then taunted Charles and was ready to kill him but Betsy's mind resurfaced and blocked David's powers. Colossus then crushed Betsy and David beneath a car, killing them both. Betsy's mind was later transferred to a new body and she was reborn. David is still believed to be dead.

Proteus possessing Morph

Earth-58163

In the House of M reality Proteus came across the Exiles and became a recurring villain. He is currently inhabiting the body of Morph, and brainwashed into thinking he is Morph. Since Morph's body is made of unstable molecules it doesn't break down, so Proteus doesn't have to change host body.