Doctor Light's History
Dr. Arthur Light is a ghostly criminal mastermind who could create light-based constructs.
A.R.G.U.S.
Dr. Arthur Light lived a surprisingly bland life as an A.R.G.U.S. scientist, until the day he was called in at midnight to investigate a communications device recovered from a secret. Exposed to strange radiation due to the villain who was communicating with him, he gained energy draining powers.
Discovering that he would drain energy from nearby artificial sources, he was locked in a small room in case this spread to humans. In this state of extremes, he was approached by Amanda Waller, who offered him a deal, remain in the cell for the rest of his natural life, or agree to join her super hero team and begin work on a cure.
While on the team, he was placed in close proximity to Superman, which given the tense situation and a super-villain plot, led to Arthur involuntarily triggering Superman's heat vision and dying.
Life after death
His corpse was examined by A.R.G.U.S., then used as an explosive device by the Secret Society, demolishing a large part of A.R.GU.S. main facility.
However, not even death could give Light peace, and he was recruited by the Crimson Men, who claimed they could make him human again, and sent him out to kill Steve Trevor. However, Trevor made him realize that he was still dead, and he vanished, much as the Crimson Men had assumed he would.
Radiant Men
Later on, when Defiance was attacked by light-based constructs called 'Radiant Men' in the Chetlan United Atlantic Islands, it was revealed that Doctor Light himself was behind their presence, who was now living in asylum on a remote island to himself in exchange for providing the dictator of Chetland Uai the Radiant Men's protection.
Deathstroke confronts Light, but instead of fighting, the two had coffee. It was revealed then that Doctor Light was once a villain before working with A.R.G.U.S, and had worked with Deathstroke at one point, and soon, also revealed that he was still dead, no longer human, but rather a reconstructed being of pure light. Slade tried to ask for a favor from Arthur, hoping that he would be able to help him after getting sent for by The Society. Light was unable to help, and once Terra arrived to help Defiance, Deathstroke left, but not without convincing Arthur to go back to his evil ways after his initial denial.
When Deathstroke was later killed, Light is the host of his funeral. When Jericho arrived to try and wreck the ceremony and capture the villains present, he tried to plead with Superman to help, who was watching from the skies, only for it to be revealed that he was only a construct of Light's, used to ensure that things would go peacefully.
