Kevin had reality-warping and possession powers and lived most of his life in forced seclusion at his mother's Muir Island research facility.

[1] Moira left Joseph without telling him she was pregnant and raised Kevin at her Mutant Research Centre on Muir Island, off the coast of Scotland.

In the ensuing fight, Kevin rejected the Mutant X label and named himself Proteus after the Greek god of myth and the cell in which he had been confined.

[13] Some time later, Mr. Sinister and the Gamesmaster also attempted to recreate Proteus by stealing a disc containing his DNA matrix, but were prevented by Nightcrawler, Shadowcat, and Rachel Summers.

Just as before, Moira MacTaggert discovered her son Kevin possessed vast mutant powers that were eating away at his body and tried to cure him of this affliction, but in this new reality, any attempt to "cure" mutation was a capital offense, and Magneto's Sentinels destroyed Moira's lab on Muir Island, setting Kevin loose.

[16] Perhaps due to lingering memories from his time possessing Mimic, Proteus became obsessed with Blink,[17] who tricked him into wearing a portable Behavior Modification System and brainwashed him into believing himself to actually be Morph.

[18] He required regular manipulation by the Behavior Modification System to maintain the brainwashing, but the device was destroyed by chance during a fight between Psylocke and Sabretooth.

[19] Morph's consciousness eventually reawakened and confronted Proteus, offering him chance to work together and share his body and powers in order to do good.

[22] When Destiny tried telepathically contacting her foster-daughter Rogue, she instead found Blindfold and passed on her vision (and unwittingly a portion of Proteus' energy).

He demonstrated the ability to possess several X-Men simultaneously, but was ultimately defeated when Magneto disrupted his energy signature, killing him once more.

Following that, he had only a few brief times to see the world before he was dispersed, but he had spent ten thousand years on the Astral Plane reflecting on the harm he had caused others and now wished only to be left alone.

Proteus has at times exhibited the ability to transport himself inter-dimensionally, though it's unknown if this is an innate power or if he needed to use a connection to the Panoptichron to accomplish this.

[volume & issue needed] After his revival through Destiny during the events of Necrosha, Proteus is shown to be able to possess multiple individuals simultaneously.

[30] At one point, Proteus compares Mitchell's fate (as seen in the Star Trek TV series episode "Where No Man Has Gone Before") to the kind of anti-mutant prejudice that the X-Men are fighting.

Proteus killed thousands of people across the world in an attempt to discredit the X-Men, including Psylocke's partner Dai Thomas, an agent of S.T.R.I.K.E.

He comes into conflict with the X-Men while searching for his father, but Professor X manages to calm him using his psychic powers, allowing him to reconcile with his parents.