Calvin Rankin was raised by his father Ronald Rankin, who was experimenting with genetics. Once when Calvin was left alone and caused a lab accident which gave him his copying powers. His father, afraid that others would despise him went into hiding with Calvin in a cave, where his father was building a machine that would take away his powers. The villagers found this out and attacked the Rankins' causing a cave-in, killing Ronald.
Years later while in college Calvin met Hank McCoy and Bobby Drake. He realized after using their powers that they were Iceman and Beast of the X-Men. He then later was in a shop were Jean Grey was. He developed telekinetic powers and realized that she was Marvel Girl. He then proceeded to follow her back to the Mansion, where he introduced himself and asked to join the X-Men. After revealing his plan to them they tussled until Calvin was able to capture Jean and hold her hostage. Calvin then took her to the cave where his father had died and planned on using the machine his father created to make the powers he copies permanent. Not realizing that it would instead take away his powers he used the machine and became powerless. Xavier then removed his memories of the X-men and Calvin returned to college.
Later during a lab accident in college he regained his powers and memory of the X-Men. Seeking revenge he demanded that he become a member of X-Men. Xavier reluctantly accepted and made Calvin the deputy leader. During the next several missions Calvin faced off against Banshee, Ogre and the Factor Three. After that Calvin was offended by Cyclops and attacked him. Xavier finally fed up with Calvin's attitude kicked him off of the team. Calvin left the mansion later to find the Super-Adaptoid attacking the X-Men. Hoping to become even more powerful Calvin offered to join the Adaptoid in his plan to conquer the earth. But upon learning he would become a mindless pawn, he changed his mind and attacked the Adaptoid, losing his powers in the process.
Calvin then returned to school until his powers started to return. This time however his powers where drawing the life force of those around him. Frightened he fled to Canada were his girlfriend, Vera Cantor asked Hank McCoy to help him in finding a cure. Unfortunately the Hulk felt Calvin's power and sought to destroy the source. As the Hulk grew closer Calvin started to absorb the radiation which gave the Hulk his strength. While the Hulk and Beast fought Calvin absorbed too much radiation and died of poisoning. Calvin was then buried in an undisclosed location.
Years later somehow Calvin absorbed the healing factor and powers of Wolverine and was brought back to life, believing himself to be Wolverine. He again encountered the Hulk and later learned that his father was connected to Weapon X. Calvin then regained his memories and the real Wolverine arranged for Calvin to spend some time in Japan to help learn to control his powers.
Years later in Siberia, X-Force found him and tried to calm him down after they crashed into a station nearby. Sometime later Mimic formed an alliance with Onslaught, who upgraded his powers in exchange for his services. He also allied himself with a man known as Sledge who also upgraded his powers.
Sometime later Excalibur was searching for Xavier after the Operation: Zero Tolerance fiasco and instead found Mimic being held hostage by rogue Sentinels. Confused he attacked the members of Excalibur and ultimately lost. They then took him to their headquarters where he recuperated and attended the wedding of Captain Britain and Meggan.
Weeks later he for some unknown reason joined the new Brotherhood Of Mutants and helped the X-Men defeat Cerebro. He then continued to work with the Brotherhood when they tried to capture X-51 a.k.a. Machine Man. They failed and Calvin was captured. Later while being held prisoner Valerie Cooper came and consoled him and offered him a way out of prison, which he took. He was then alongside the Brotherhood affected by a beam sent down by the High Evolutionary in order to de-power all of Earths mutants. The beam caused Calvin to lose his powers momentarily, but he quickly regained them moments after the beam was reversed.
Later Calvin spent an unknown amount of time on Muir Island with Dr. Moira MacTaggert in hopes of finding peace. It was here that Moira figured out that Calvin had Bipolar Disorder. Under her care Calvin began to take mood stabilizers and anti-anxiety medication.
Calvin was seen as a captive of the Thunderbolts after Civil War|recent developments as a captive alongside hundreds of other criminals in the Folding Castle Detention Quadrant. It is unknown if Calvin joined the Thunderbolts or if was simply held by them as a prisoner.
After the Secret Invasion by the Skrulls Calvin was in some sort of unidentified incident in which he came into contact with Norman Osborn. During this encounter Norman recruited Calvin into the newest government sponsored incarnation of the X-Men lead by Emma Frost. During an incident in San Francisco, Calvin and his X-Men were called out to quell a riot instigated by the mutants Hellion, Meld, Lorelei Travis, Avalanche, Match, Adam X, and Sunspot. After dispersing the mutant rioters Emma's team of X-Men returned to Alcatraz Island, the west coast headquarters of H.A.M.M.E.R., where Mimic and his fellow X-Men were confronted by Norman Osborn's Avengers. After a small skirmish between Daken and Hawkeye the two teams calmed their more volatile members down. Mimic even threatened Hawkeye with a shiv made out of ice. The two teams then went their respective ways until Simon Trask activated his new "Bio-Sentinels" out of his followers at St. Francis Hospital. These Sentinels caused mayhem and panic in downtown San Francisco until Emma's X-Men were called onto the scene. After engaging these Sentinels, Calvin tried to reason with one of the robots but was reprimanded by fellow teammate Weapon Omega. Swiftly taking care of the Sentinels, Calvin and his team apprehended Trask. Calvin and his team continued to patrol the streets and arrest criminals and unruly mutants. Having been celebrated as heroes by the public, Calvin and his X-Men then responded to a distress call on Alcatraz as X-Force and other X-Men freed the tortured mutant prisoners including Beast. As they arrived on the scene Daken confronted his father, but was put down by Emma Frost. Confused by this Calvin tried to talk with Emma, but was knocked out by Namor who slammed Calvin into a wall. Emma, Namor, Cloak, Dagger, and X-Force left Alcatraz via a stepping stone created by Magik. Recovering, Calvin and his teammates Dark Beast, Weapon Omega, Daken, and Osborn's Avengers prepared for an all out battle against Cyclops's X-Men and the remaining mutants of San Francisco. Calvin and his teammates then assaulted the newly created island of Utopia to attack and apprehend the X-Men. Calvin confronted former teammate Iceman who quickly grounded Calvin. Seeing their opportunity the Young X-Men and other young mutants pounced on Mimic, overpowering him. Calvin managed to overpower and escape alongside his teammates. After recovering, Calvin attended a huge news conference set up by Osborn. During the conference Osborn demonized Cyclops and his newly constructed island of Utopia. Osborn also congratulated and praised the efforts of his X-Men, Calvin among them.
After the Utopia incident Calvin was put under the psychiatric care of Dr. Karla Sofen due to his depression. During these sessions Calvin will often talk about his depression and his urge to be a good person. Calvin, alongside Norman Osborn's other X-Men, were then gathered for a briefing about the small town of Burton, California coming under psychic attack from a being claiming to be an X-Man. Calvin, along with his teammates, were then sent to Burton to investigate things. There they interviewed a victim of the attack, but suddenly the victim gained mutant powers which were instantly copied by Weapon Omega and Calvin. Omega could not cope with the copied powers and flew off whereas Calvin gained the ability to see into the future. In one of his visions he say himself with his old girlfriend Vera Cantor, apparently they had married, and their child. The vision ends in Calvin's powers going out of control and accidentally killing both Vera and his child. Shaken from this vision, Calvin was unable to help his teammates subdue Omega until Dark Beast sprayed him with some sort of power enhancing, psychoactive rage inducing drug. Due to the drug, Calvin became crazed and started to attack Omega. Somehow shaking off the effects of the drug and the copied powers, Calvin was able to subdue Omega and return to H.A.M.M.E.R. headquarters with his teammates who found out that the psychic entity was none other than Nate Grey, otherwise known as X-Man. With this new knowledge Norman gave them a new mission: capture Nate Grey. The team then went to the Psi-Division of H.A.M.M.E.R. to find Nate. While there they were met by the Psi-Division commander Alex Jarl to help them utilize the psychic division to its fullest potential. Jarl utilized all of his psychics to search for Nate, but Nate used their combined psi-energy to restore his physical form and to catch "up-to-date" on the world since he has been gone, including the rise of Norman Osborn. Not too happy with how the world was going, Nate started to attack H.A.M.M.E.R. facilities across the country and coming into contact with Norman's Avengers. Called into action, Calvin and his team joined the fray. During the fight Calvin saved Nate's life from Hawkeye, really Bullseye, in order to copy his powers to find out more about his future. After copying his powers Calvin joined Nate inside the time-stream where they talked about Calvin's vision and the way Nate perceives the world, however Ares, being a god, found them and ended the discussion, and before Nate was knocked unconscious Nate called out for Calvin to be a hero, but it was too late. However, before Nate was taken away, a brilliant flash of light came from Nate and he disappeared, leaving a charred corpse.
Nate was alive though and took possession of Norman Osborn. Mystique, being a master of disguise recognized this and warned her teammates as well as the possessed Osborn that she knew. Determined to fix this, Calvin and his team visited the Psi division again and utilizing the psychics and Calvin's psychic powers had himself and teammates transported into the mind of Norman Osborn. While there, Nate led the team to the part of Norman's mind which housed the Green Goblin entity. Accidentally freeing him, the team set out to find the Goblin and Norman. Once the Goblin was found, he sliced Mystique's neck; Calvin was the only person on the team who seemed to care about her being hurt. Healing herself, the team pressed on against the Goblin, however the Goblin trapped Calvin and Omega and used his willpower to gain control of them. The three of them then broke into the area where Nate and Norman were dueling it out for control of Norman's body. The Goblin then used Calvin and Omega to draw out all of Nate's power, leaving him helpless and restoring order to Norman's mind. Ensnared and restrained, Nate told Calvin that if he would have been a hero he could have helped put his premonition into perspective and helped him take control of his life and would have helped Mystique and Omega as well. Nate was then carted off to the Omega Machine while Calvin, Mystique, and Omega were visibly saddened and reflected on what they had done.
After Osborn was deposed by Earth's Mightest Heroes there came a great crisis involving the Asgardians. During this time the Initiative called as many heroes to arms as they could in order to control the chaos and the riots that were caused by Sin and The Serpent. Calvin was in this crowd of heroes who answered the call. In what capacity and where he helped remains unknown.
Some time later, Calvin and Weapon Omega, Michael Pointer, crash landed at the newly formed Jean Grey School for Higher Learning in seek of help from the local X-Men faction; Weapon Omega's powers had begun to fluctuate out of control essentially making him a human time-bomb. During the time with the X-Men, Calvin showed true remorse for his past misdeeds and creating a special bond with Rogue. During this time Beast was having trouble figuring a way to safely dissipate Omega's energy, until Calvin came up with the idea of Rogue and himself siphoning off the excess energy from Michael Pointer. Through cooperation, Calvin and the other X-Men were able to put Michael in a state of suspended animation until they could figure out a true way to safely expel all the chaotic energy trapped within his body. Calvin, seeking friendship and a way to reconcile with his abilities and past, was offered a teaching position at the school and a place on the team by Rogue; he gladly accepted the offer and began joining the team on adventures which eventually led him into direct conflict with the Avengers.
After the conflict between the Avengers and X-Men, Calvin, feeling doubt and unsure of his identity due to the nature of his powers, helped quell a riot at a superhuman prison with Rogue; during the event Calvin learned to reconcile his identity issues and doubts with the help of Rogue while battling a multitude of super powered criminals. Upon returning, Calvin told Rogue that due to Omega's recovery he, and Michael, would be leaving the school to start a new chapter in their lives. Sometime later, Omega and Calvin were helping with relief effort in a disaster area when they were approached by the anonymous X-Man known as ForgetMeNot, whose powers made him forgettable to those around him; seeking their help in order to purge him of his powers they were interrupted by the untimely arrival of Cyclops, Magik, Emma Frost, and Magneto who sought to recruit Weapon Omega and Calvin for their new team. Causing a disruption, and eventual fight, the two teams collided in battle until, with the mixture of Omega, ForgetMeNot, and Calvin's powers they were able to momentarily hide themselves from the X-Men; once they left Calvin and Omega forgot that ForgetMeNot was there as he slinked away in depression.
With the ultimate demise of the universe and the formation of Battleworld, his fate and current whereabouts are unknown.