Bruce Wayne's life started out good enough. His father, Thomas Wayne, was a wealthy physician who had regularly donated his time and skills to the poor of Gotham City. His mother Martha was skilled in founding charity functions as well. Both of them were good friends of Leslie Tompkins, who had studied in medical school with Thomas Wayne.
However, his life changed, both cruelly and dramatically, when the boy had witnessed both his parents murdered by a common street thug during a mugging. Leslie Tompkins, who lived nearby and had a clinic there, had comforted the boy after the crime occurred. After his parents funeral, he had sworn upon his parents' graves that he would dedicate his life to fight those who prey upon the weak and helpless.
From that day forward, Wayne had studied every science in the fighting of crime, which included psychology and forensics. He even extended his studies into various skills, which included escapology. He even traveled the world to study the various martial arts – which included niujutsu (during this, he ran into Kiyotai Ken, which he would fight later on in his life).
However, try as he might, he found one weakness in his battle – he needed to exploit the cowardice within all criminals. During this time, he had met Andrea Beaumont, whom he had fallen in love with. He even considered marrying her, but she had broken off the marriage when she fled with her father from the Sal Valestra Gang (years later, Beaumont would become the Phantasm and seek revenge on the Valestra Gang and the Joker for the death of her father). But when Bruce proposed to Andrea, he found that underneath his home, Wayne Manor, there was a large cave with a great number of bats. He then found what all criminals feared – the darkness. After Andrea (along with her father) had fled to Europe, he became the greatest terror of all evildoers in the world – a grim shadow that everyone would call "The Caped Crusader" and "The Dark Knight" – the Batman!
As the Batman, Bruce Wayne possesses Olympic-standard gymnastic ability, as well as his own unique fighting discipline, gleaned from the many styles he studied. He also is an expert forensic scientist, using the latest in the science to find clues to various crimes, not to mention extensive knowledge on many criminals. But he also has access to cutting-edge technology to aid him. The computer systems inside the Batcave is at an equal, if not greater, to many law-enforcement agencies. However, many of the various devices and vehicles he uses are often provided by either dummy corporations – or grateful individuals that he saved as the Batman who lend their services to him.
Batman also has an unofficial relationship with Gotham Police Commissioner James W. Gordon, and would often consult him on many matters. And over time, several other individuals would actively aid him; Dick Grayson and Tim Drake both became Robin (Grayson later became Nightwing), and Gordon's daughter Barbara would eventually become Batgirl.
Batman's relationship with Superman, while sometimes adversarial (mostly because of Batman's suspicious nature), is friendly, and the two aided each other from time-to-time. And although he is an infrequent member of the Justice League, Batman has, through secret channels within Wayne Enterprises, supplied them with their orbiting headquarters, the Watchtower.
However, in time there was one enemy that Batman couldn't defeat – that would be time itself. When his heart finally became faulty during a rescue, Wayne decided to hang-up the costume of the Batman once and for all, and dedicate himself to Wayne Enterprises, which was the target of the corrupt corporate raider Derek Powers. Powers would later be successful, renaming the company Wayne-Powers, and use the resources for his own aims – which included producing weapons of mass destruction, something the charity-minded Wayne avoided (Powers would later become the radioactive menace Blight). Thus Wayne became a virtual recluse, his only company a black Great Dane named Ace, whom he had rescued some years before.
But in time, he would be drawn back into the fight against evil when a former juvenile delinquent, Terry McGuiness, came into his life. Although reluctant to take the boy one, he approved of Terry becoming the new Batman. It would be later that Wayne would find out that Terry was, in fact, his genetic son.