Daxam - Tumblr Posts
When Mon-el arrived on Earth AI with amnesia, speaking Kryptonian, and with super-powers identical to his own, Superboy thought he must be from Krypton. His strong family resemblance led him to hope he might even be related, so he gave him his Kryptonian last name ‘el’.
But Mon-el was neither Kryptonian nor related. He was an explorer from the planet Daxam, a planet similar to Krypton in a distant galaxy. He had landed on Krypton a few months before it exploded and lived there long enough to learn the language. When he attempted to return to Daxam, his inter-galactic displacement drive malfunctioned. Its flight control system mapped a course to the nearest star system with humanoid life similar to his own - Earth AI.
Unfortunately the environment of Earth AI is poisonous to Daxamites. The super-powers he gained due to the yellow sun saved him from immediate death, but eventually he became fatally ill. Superboy put him in the Phantom Zone, a kind of ethereal dimension where his body is in stasis, until a cure can be found for his poisoning.