The Birth: It all started in a small visiting circus in Metropolis. Cat, Adam, Jimmy and Clark decided to take some time off from their hectic schedules and visit the circus. And as always, their reporter instincts got the better of them as they snooped up "The Amazing Brainiac", a two-bit metalist who'd amaze the crowd with cheap mind tricks. Brainiac was by no means one of those common charlatans; he did have this mental ability, a gift if you may, and it was this gift that led him on the rugged path to the bottom. In his dreams, Brainiac's mind would reach out to touch the universe and so he came in contact with Vril Dox; a being from the planet Colu. Vril Dox was a scientist with one of his special interests lying in the infant science of teleportation. Vril Dox built a matter transmitter and tried to teleport himself around the world. His atoms disassembled according to plan but failed to reassemble ! He became a demolished individual, possessing only mind and personality but deviod of any body, any physical aspects. It was when his mind touched Brainiac's that he was able to form a bond between the two minds and there began the unending trauma for "The Amazing Brainiac".
Brainiac made his historical appearance in Action Comics #242 (July, 1958); and the canonical first appearance in the Adventures Of Superman #438 (March 1988).

The Alter Ego: Brainiac is only his show name, his real name is Milton Fine. A simple docile fellow, he was always being nagged at by his dominating wife, Janet for not putting his power to a greater and more profitable use. After the first major assualt by Vril Dox on Fine's mind, Fine became hysterical. Doctors blamed the whole blasted thing on an errant gene. Their diagnosis: Besides his mutant gene, it was a classic case of paranoia with a deepening psychosis. As for his story about aliens from Colu, they claimed it was part of the psychosis. His limited educational background did not provide him with the necessary data for comprehending what had happened to him. So he just invented an explanation that he could grasp. Well, that was it. His social life was over and he was sent to the loony farm.

The Legend: When Milton Fine's mind met Vril Dox's personality (which was at the time devoid of body) Dox formed a mental bond between the two minds and tried to take control of Fine's mind and body. Dox suceeded in invading Milton Fine's body but his show of destrustive power in the circus attracted Superman. The two slugged it out, with Superman coming on top. With Brainiac in the psychiatric ward the incident made big news. Hearing of this power; Lex Luthor had him brought to one of his special medical units. Fine was apparently dying of a brain tumor which Luthor's doctors took care off. But Luthor merely didn't remove the tumor, he replaced it with a special bionic circuitry which worked similarly to a cattle prod, thereby giving him complete control of Milton Fine. And to dissuade Fine from attempting anything on Luthor, he had a failsafe also built into the circuitry.
Fine's invader, Vril Dox was later able to outsmart Luthor and turn the tables. When Brainiac was taken to the Lexcorp facility his powers were enhanced tremendously. His telepathic and psychokinetic powers are now at their peak. Brainiac can mentally control several people at once and can link his mind with any computer system.
Brainiac alsoassumed control of the rampaging monster Doomsday (see Doomsday) for yet another attack against Superman. Much later, when a Superman body appeared in Metropolis, suspicion was cast on Kal-El as to whether he was indeed the real deal. Problem was even Professor Emil Hamilton examined the dead "Superman" body and said it was 100% kryptonian. Superman was in a fix and even went to the New Gods home planet to check whether Brainiac was imprisoned there. Brainiac was indeed a vegetable, and could do nothing with anybody's help. But as it turned out, Brainiac was in a deep sleep rather than a coma, as he wanted everyone to think otherwise. And it was his tricks that made everyone believe that the body in the tomb was real.
Later on, Brainiac was brought to the Lovelace Mental Institution for treatment to allow Milton Fine take control over his own body. Brainiac's mind was weak at the time, but when he heard that one of the inmates thought himself to be Superman, he regained control over Fine's body and in his usual style of theatrics, attracted Superman to the instituition. Using his power, Brainiac was able to trap Superman's mind in Chas Cassidy's body (the kid who thought he was Superman) and thereby take control of Supes body just as he had done years ago with Milton Fine. As Superman, he sealed Metropolis, letting no-one out or in and then began using the populace as his storage vessels. In the end, Superman and the kid, Chas were able to stop Brainiac who was once again trapped in Milton Fine's body.

Adventures of Superman #438