Calvin Rankin was a regular boy until an accident changed his life: his father, Ronald Ranking, was making some experiments involving mutant genes. Calvin one day entered his lab and was intoxicated with some gas. This substance gave him his power: the ability to "mimic" other superhuman powers and regular human abilities. He knew he had powers when he realized he could mimic his friends sports abilities or his teachers intelligence. His "friends" though that he was a mutant, and tried to kill the boy. He escaped to his dad lab. His father tried to close the door to the place from the attackers, but an explosion took his life and left young Rankin alone. He went to college with a brash attitude, and things seemed to be normal.
One day, he met a librarian, Vera Canton, and her boyfriend, Henry McCoy, a.k.a. theBeast. Jealousy, he confronted him and his friend, Iceman, and got theirs powers. With no control, he just ran away. Other day he met Jean Grey, the now named Phoenix, and got her psionic powers. Hiding them this time, Calvin followed Jean to the X-Mansion and there helped the X-Men defeat the Puppet Master, who was attacking the group. Professor X asked him to join the X-Men, and he accepted. Since Cyclops was having problems with the leadership of the group, Xavier invited Rankin to be the new field leader. The Mimic became an X-Men, but his spirit was too aggressive: Charles eventually asked him to leave the group. He allied himself with the Superadptoid and attacked the team. He realized that the android was just using him, and rebelled against him. By that time he had lost the powers he had kept from the X-Men and, in a visit to the destroyed lab of his father, discovered that he had implanted a failsafe device on his powers that would keep them in check if he used them to often. He began to wonder across the U.S. and disappeared.
Years later, the Hulk found Calvin and, after a battle, he appeared to have committed suicide himself by falling in a gamma caldron. Wolverine, some time later, would find himself accused of crimes he didn´t commit. In search for the responsible, he found the Mimic, now copying the looks of the target of his powers. Both men tried to find some answers and went to the lab where the experiment took place once again. There was a hologram of Calvin´s father there, where he explained his powers and the amount of concentration and responsibility that came with them. Logan sent Calvin to a Japanese monastery, where he could live in peace.
More years came, and Calvin reappeared again, fighting against X-Force, with the power of the original X-Men. He was defeated by then, but showed up again with the Blob under someone´s order. By that time, it seemed that it was Onslaught his master, but it´s clear now that someone had enhanced his abilities
Some months later, in a mission where Excalibur was trying to find the missing Professor X, they found the Mimic trapped in one of the Zero Tolerance´s base. They released him and he joined the team for a short time. Most recently, Calvin reappeared by the side of a new Brotherhood, that managed to find and release Professor X from his confinement, so he could them fight Cerebro. In a battle with the X-Men against the computer villain, all the members of this Brotherhood were captured and are now missing.
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