Mutant shape-shifting serial killer
Proteus is one of the strongest and deadliest mutants ever born. Despite being incredibly powerful, Proteus was not fortunate enough to have a happy life. Even his conception was under unpleasant circumstances. He was the son of Moira MacTaggert and her sinister husband, Joseph MacTaggert, who forced Moira into an unhappy marriage. Kevin was conceived after his mother, Moira, took a severe beating from his father, Joseph. After this traumatic experience, Moira left Joseph. Moira didn’t even notify him that she was pregnant with his child.
Moira and Kevin lived on Muir Island, off the coast of Scotland. Kevin eventually began manifesting his mutant abilities and became a danger to everyone around him. His abilities gave him an uncontrollable hunger for energy. To protect herself and others, Moira was forced to confine Kevin. To keep the truth about her son secret, she began to describe him to others only as Mutant X.
For years, Kevin remained inside his cell. Recently, Moira MacTaggert was declared criminal for attempting to cure her son Kevin of the mutant gene and his psychosis. King Magneto’s mutant supremacy saw this as an act against mutant kind, and Sentinels were dispatched to destroy Muir Island and capture Moira. Though Moira escaped, Kevin was also freed, sending him on a gruesome killing spree that was attributed to Moira as failed experiments, as she chased him across the globe.
When the reality-hopping Exiles caught Proteus’s attention, Moira emerged from hiding to warn them about her son, who was intrigued by their presence and desired to ruin the realities they attempted to fix. When he attacked the team, Moira shot him, exposing him to the metal that was his deadly allergy and only weakness, forcing him to find a new body. Unsurprisingly, he chose his mother’s—rather than allow her son to possess her and use her against them, Moira committed suicide.
Proteus managed to escape by stealing data from the Panoptichron. He has inhabited the bodies of Angel Salvadore (House of M), Justice (New Universe) and Hulk (2099). He has also taken the body of Mimic of the Exiles. All of these bodies have not lasted for long and eventually withered away, with the exception of Angel Salvadore and Mimic.
Proteus stated that he could not stop thinking about Blink. Whether it was because he still had some of Mimic’s memories or because he actually felt something for her is not yet clear. He stated he was tired of fighting and that he just wanted to talk, but before he could say anything Longshot came in and shielded Blink, allowing her to teleport to safety. It was revealed by Proteus himself that his mind is able to recall all memories and feelings of his previous hosts. Blink tricked Proteus into wearing a portable Behavior Modification System (from Squadron Supreme’s world), which she teleported into the crown he was wearing. The device brainwashed him into believing he was actually Morph, and left him able to recall only Morph’s memories prior to his possession. Unaware of his true identity, he began behaving exactly like Morph and a member of the Exiles, much to the discomfort of the other Exiles.
With Proteus trapped and believing he was Morph, he remained an Exile to continue fixing damaged realities. Since Morph’s body does not burn out like other hosts, Morph’s consciousness is still active beneath Proteus. Also, Proteus is immune to metal while in Morph’s body, since wearing a metal tiara did not kill him. However, concerns about some discrepancies in “Morph’s” behavior forced his teammates to plan regular brainwashings with the same device, and, eventually, put him in stasis whenever his behavior would change again. However, that device was destroyed when Psylocke and Sabretooth fought so intensely that they shook the Crystal Palace, causing a bookcase to fall on Morph’s head, shattering the device. With the device shattered, it was only a matter of time before Proteus would re-emerge.
Breaking free of the MNS control, Proteus banished or killed every field agent of the Exiles except Morph, possessing Sabretooth in the process. He then escaped to the Aniverse, where he took control of the Black King’s Harvesters and used them to capture Cyclops and Phoenix’s son Nathan, as well as Clarice of Academy X. Before he could further his plans, however, the freed Morph showed up with a new team of Exiles, and recaptured Proteus.