Origin

Formerly a U.S. soldier, Apollo was a member of an secret experimental academy team created by the insane former Stormwatch Weatherman, Henry Bendix. Unlike his lover, the Midnighter, 

Midnighter

The Authority

Apollo's brief vacation into normalcy was to be short-lived. Less than a year after Apollo and Midnighter's retirement, nearly the entire Stormwatch team was slaughtered in an Aliens/Stormwatch Crossover. Jenny Sparks would develop her vision for a new team, known as The Authority  and she approached Apollo and Midnighter about joining. Jenny originally only asked Apollo to join because she knew that Midnighter would reluctantly accompany Apollo anywhere (part of the reason they were nicknamed "Bert" and "Ernie") Apollo would then take his place as "The Sun God," on a team consisting of Midnighter, Swift, Jack Hawksmoor, Engineer, Doctor, and Jenny Sparks. His relationship with the Midnighter would only be hinted at until the Sliding Albion Story Arc, in which it was confirmed they were a couple.

Violation

Warning: Discussion of Sexual Abuse

In the Fourth story-arc (Authority, Vol 1 #14), The Authority battled for possession of Baby Jenny, the reincarnation of Jenny Sparks who would eventually grow up to be Jenny Quantum. During this battle, Apollo faces off with a character known as The Commander, an overly-macho testosterone driven meta-human who sexually assaults innocent people in the hospitals that he searches. Apollo is beaten badly by The Commander and his two companions, and the comic strongly implies that he is then raped against the hood of a car, his body left to be discovered by the Midnighter, who is seen holding Apollo and crying.

Following this scene in Authority, Vol 1 #14, Apollo is seen pensively watching TV when the Midnighter comes into their rooms. When asked what he's doing, he admits to thinking,

To which Midnighter replies, "God, I just love you to bits sometimes."

When Apollo encounters The Commander at the end of the story-arc, he quickly gains the upper hand. But when The Commander suggests that Apollo can't kill him because he "gives him feelings he only read about in Cosmopolitan Magazine," Apollo tells him,S

The scene concludes with Midnighter standing over The Commander's now paraplegics body, holding a large jackhammer.

In a later story-arc where Apollo is being held prison by The New Authority, his replacement, Teuton,

Teuton

Soon the Authority would finally take over the American government after they caused the deaths of an alien group traveling through the Bleed. The team was able to take power without out any trouble. However keeping that power was far more troublesome. Enemies such as Stormwatch: Team Achilles did not approve of the takeover and Midnighter and Apollo were sent on a mission to raid their base which almost ended with them losing their lives in the process and they were given the task of dismantling the American training camp for SPBs. Soon Midnighter was visited by a future Apollo warning him he would become a tyrant and he needed to break up the team to stop this from coming to pass. Meanwhile a group of former heroes called the Sons of Liberty had caused americans upset with the teams rule to riot and after a nuclear explosion in Washington the team disbanded and Midnighter left Apollo to raise Jenny on his won. However after three years Jenny decided to speed up her age going from 8 to 14, rebuilt the team and it discovered this was all a plot made by Henry Bendix and a revived Rose Tattoo. Bendix revealed he had secretly taken control of Midnighter using nanites and forced to attack and beat the team including Apollo. However he was able to slightly gain control asking Apollo to take his life, but Jenny and Engineer were able to free him and in revenge he killed Bendix himself.

Powers

Apollo's abilities are powered by solar energy, which he absorbs form UV rays of the sun and can store in limited quantities inside his body. When fully charged, Apollo can withstand the molten heat at the Earth's core, destroy entire spaceships by flying through them at intense speeds, and practically level entire city blocks.  He's been known to circle the globe in sixty seconds. But although the range and extent of his powers are astounding, it is possible for his energy stores to become depleted if kept out of the sun long enough.

Power of the Sun God

When the political powers of Earth attempted to overpower The Authority and replace them with The New Authority (consisting of Surgeon, Teuton, Machine, Last Call, Rush, Street, and Union Jack), they captured Apollo and gave him to Last Call, who kept him chained in a dark lower level of the Carrier. During his time in captivity, Apollo's powers were reduced to that of a regular human being, though he still did not require food or water to survive. Last Call beat him severely, breaking his nose and many of his bones, as well as burning him with cigarettes and drawing blood from his weakened skin. In this extreme case, exposure to the Baby universe that powered the Carrier was required to replenish Apollo depleted energy reserves. In less drastic situations, direct contact with sunlight for anywhere from twenty seconds to two minutes will power him sufficiently to fly and fight.