Charles "Charlie" Evans was marooned on the desolate planet Thasus while very young, the only survivor of a spaceship crash. He spent years there before the Antares discovered him in 2266, by which time he was 17-years-old. The Antares transfered Evans to the USS Enterprise so that he might be reunited with his only known relatives on Colony 5.
Evans claimed to have learned to speak by talking to the crashed ship's memory banks. He'd survived on food concentrates for a time, discovering edible native foods before his supplies were exhausted. Spock and McCoy debated this, Spock contending that Charlie's survival argued for the existence of some form of intelligent life on Thasus. There were gaps in Charlie's knowledge, and he demonstrated great immaturity on a number of occasions.
Evans demonstrated a number of strong psionic powers, eventually taking control of the Enterprise. Kirk speculated that he might be a Thasian, but McCoy's medical scans showed Evans' physiology matched that of 23rd century Humans, leading McCoy to believe that, despite his abilities, Evans was Human.
The Thasians, having discovered Evans' departure from their world, caught up to him before the Enterprise reached Colony 5. Claiming it was impossible for Evans to live a normal life, they transported him aboard their vessel and departed.
The Thasians had granted Evans his wide array of powers so that he could survive on their inhospitable world. Although they were able to restrain him temporarily, they were unable or unwilling to remove the powers.
Evans' powers included:
- The ability to make matter vanish, to create matter, and to rearrange the structure of matter
- The ability to influence the operation of mechanical devices
- The ability to alter the physiology of living beings and to influence their mental processes
Pressed to explain what became of the objects he made "go away", Evans could not or would not do so. Whatever happened to them, they were not destroyed, since the Thasians were able to restore them. It is likely that Evans did not fully understand his powers. (TOS: "Charlie X")