Secret Origin of the Red Sun of Krypton & Krypton Itself!

The story is legendary and often repeated. The planet Krypton had a thriving civilization existing on it for thousands of years, until internal pressured from within culminated in the world exploding. From this world, the last son and daughter of Krypton, along with scant few fellow survivors, were jettisoned from this condemned globe. And so this tale was told... until the untold secret origin of Krypton and its sun was revealed!

Kal-El, the last son of Krypton-One who became the Superman, discovered a mysterious orange sun entering Earth-One's solar system. Intercepting it, he was pulled within and met its creators, the  ancient gaseous beings known as the Sun-Thrivers, whose existence had depended on their encasing themselves within an artificial red sun. However, the sun needed a counter-balance to maintain its internal gravity, and so pulled together enough mass to form a large planet within that red  sun's orbit. This planet became Krypton-One, and as mentioned by the Harbinger during the Crisis on Infinite Earths, "The Earth... and all the planets were duplicated" aside from the world known as Oa. 

And, in fact, there was a Krypton-Two, Krypton-Three, Krypton-Prime... indeed a Krypton and its corresponding red sun, in every universe across the Multiverse. All created in the same manner, through each universe's version of the Sun-Thrivers. And in all cosmos save that of Earth-Three's, the mass upon which their individual Krypton was built proved unstable and doomed to extinction.

A few years after his counterpart met the Sun-Thrivers, who presented Kal-El with their new Kryptonite powered orange sun designed to replace their dying red sun, Kal-L likewise encountered twin Kryptonite powered green suns orbiting Colu-Two. Whether enlisting or enslaving his universe's Sun-Thrivers into creating them, or perhaps using other technology to accomplish this, Vandal Savage of Earth-Two used these green suns against Superman and Power Girl. Conceiving a scheme to weaken the Kryptonians, Savage syphoned their powers in order to extend his formerly immortal life. Vandal engaged Superman in battle and lost. And so, the last son and daughter of Krypton-Two, Kal-L and Kara Zor-L aka Superman and Power Girl, left this artificial planet and its suns behind without a second thought. As for Savage, two shadowy men abducted him, pulling him into Earth-One to meet Kal-El later.

And as most of Kryptonite was absorbed into Savage's suns, so too was most of this same substance absorbed into the Sun-Thriver's red sun and Krypton-One version 2.0. This lessened the threat of either Superman being exposed to this life threatening substance in the future, aside from those meteorites that fell to their native worlds previously or still floated somewhere outside the vast expanse outside the Sun-Thriver's reach.

One of the two sentient Green Kryptonite suns named Aquarius turned insane, causing its stellar twin and the other Council of Living Stars to depower and banish it from their midst. Aquarius would eventually arrive on Earth-Two, steal Starman’s Cosmic Rod allowing the entity to create a new body for itself and greatly amplify its powers.

Battling the Justice Society and, two weeks later, the Justice League, Aquarius eventually found itself within the Anti-Matter or Negative universe, where it was permanently destroyed.