Zero was originally from a planet named Earth, created as a robot made to carry out the petty revenge of a spiteful scientist. Against all odds, he became seen as a hero as he fought alongside the very one he was meant to fulfill his creator's revenge against.
For hundreds of years, he fought for those who believed in him, and despite his resilience he couldn't escape destruction forever- eventually hurtling to Earth in a heroic sacrifice in order to end a truly evil destructive force.

Finding himself reborn on another world right off the heels of a destructive meteor impact, Zero is confused by all the lush green around him- a world very different, more organic than the one he lived in before.

The first living person he encountered was a Czylph named Inti, who ended up taking the confused new Scarftail in. Inti found Zero's story of a past in a futuristic world strange and fascinating, happily and intently listening to it, wondering why such a thing would occur...

The peace wouldn't last for long, however, as the evil that had taken hold of this world had finally found the way to Inti's hiding place thanks to the landing of the meteor near it. Thanks to Zero's sword technique and Inti's magic prowess they were eventually able to escape- on a new journey to save the Czylphs imprisoned to provide power for the tyrant behind the attack, with Zero at Inti's side to protect and aid him.

As they fight together, something like affection begins to develop between them- a strong friendship and equal respect turning into... love?! Kinda gay ngl...