WARNING: This issue contains spoilers for Astonishing X-Men #8, by Charles Soule and Paulo Siqueira, in stores now.
In Astonishing X-Men, Professor X has returned to the land of the living after a lengthy and arduous battle with the Shadow King on the Astral Plane. The villain was defeated, and Charles was reunited with his precious X-Men -- but all of that came at a cost.
After all, the Professor wasn't the only one that managed to claw his way out of the metaphysical plane; in addition to Xavier's resurrection, a classic X-Men villain also came back from death. Proteus, aka Mutant X, aka Kevin MacTaggert, the son of longtime X-Men ally and friend, Moira MacTaggert, is once again counted among the living.
Proteus was last seen in Mike Carey and Clay Mann's X-Men Legacy #233, part of 2010's "Necrosha X" crossover. Although the character died in the issue, his unavoidable return was foretold. Now, eight years later, the character is back from the Astral Plane, roaming the Earth once more and already posing a dangerous threat to the citizens of London. Hoping to avoid a physical confrontation, Professor X opts for a different approach. With Psylocke in tow, the two telepaths enter the mind of Proteus, where the villain appears as the human he is supposed to be.
During the telepathic exchange, Kevin divulges a key bit of information that comes as shock to Psylocke -- a revelation that effectively rewrites an important piece of the X-Men's past, and the team's first confrontation with Proteus. He says that when he first fought the team of mutants, when they killed him, he was only ten years old, and not the adult he was believed to be.
The X-Men first went up against Proteus on Muir Island, back in 1979's Uncanny X-Men #127-128 by Chris Claremont and John Byrne. He appeared as living energy, with no body to call his own after having burnt his to a crisp. He went from possessing one character to another, appearing as a terrifying specter that the X-Men had great trouble stopping. Although they hadn't set out to kill their newest villain, Cyclops and the rest of his team realized that Proteus was unlike anything they had faced before. When he was left vulnerable for an instant, the team of mutants had no choice but to stop Proteus for good. The man made of living metal, Colossus, got hold of the villain, and beat him to death.
Colossus was one of the only ones in the world able to defeat Proteus because of the villain's apparent weakness to metal. While this turn of events was no doubt a tragedy for the X-Men, who are not out to kill their enemies, this was still viewed as a great victory considering the threat Proteus represented to the entire world.
Thanks to the newest Astonishing X-Men issue, we learn that Kevin was nothing but a child lashing out at the world. While his age was never made explicitly clear during his original appearance, readers had every right to believe that Kevin MacTaggert was well into adulthood. Not only was his speech pattern well refined, like every other character that surrounded him in the comic, he performed no actions that would lead us -- or the X-Men -- to believe he was a pre-adolescent child. The way he spoke and acted, the way he viewed the world and embraced his powers, indicated a character that was an adult.