Two-Face, the infamous Batman villian, actually used to be Gotham City District Attorney Harvey Kent. He is son of Jonathan and Martha Kent and adoptive brother of Clark Kent (Superman). His parents stopped paying attention to him after finding Clark in the Kryptonian rocket ship, who became their number 1 son. Harvey moved down the list to #2, a theme that would later surface in his 'second life,' so to speak. He never let on his anger for the Kents making Clark their favourite, rather he kept the rage and rejection buried deep inside.
During his college years he was top of his class, but his parents never noticed, as Clark had then began to develop his powers. This further cast Harvey in the shadows, so in a final effort to impress his parents he went to Gotham Law School, and rose to the ranks of District Attorney. His parents mumbled something about Gotham City being an ugly town with too much shadow motiff, and he gave up trying to impress them.
As District Attorney he was under a lot of pressure to convict the da Vinci crime family, particularly Mona Lisa "Longhair" da Vinci, the matriarch of the family. This proved to be very difficult a task because the defense claimed the crimes committed were fakes, and not really works of the da Vinci family. This angered Harvey to the extreme, and the stress caused him to break out in hives.
It got very bad when on March 16, 1987, during his opening statement, Harvey stammered in court "Harvey Kent representing the people of the state of uh uh uh.." He could not come up with the name of the state for five whole minutes and was laughed out of court. The charges against the da Vinci's were dropped. To add injury to insult, Leo "The Brush" da Vinci (creator of The Da Vinci Code) poured a bucket of acidic paint all over Harvey's face on the way out of the courthouse.
After spending all night scrubbing the paint off to no avail, Harvey snapped, and because Two-Face. He took over a gang and completely destroyed the da Vincis in order to 'make way for a new kind of crime wave,' he reportedly told the newspaper.
Since that time he has been constantly battling Batman for title of 'most mentally ill comic book character.' He does everything in twos, in keeping with his name. This includes little things like eating two meals a day, and eating tuna fish (he loves annoying 'two puns') and major aspects of his life. He is bi-sexual. Superman cannot battle him because as his brother, Two-Face knows all the spots where he is ticklish. Fortunately his reign of terror will soon end, because he has a tumour. Doctors give him 2 months to live.