Okay, after watching the third episode of the anime, I came up
with this idea involving Kirby and Meta Knight's connection
with themselves and NightMare. Please bare with me, okay?
The tyrant named NightMare could change reality at his will,
able to change himself and create things out of seemingly
nothing. He once made a blue circle monster with a sword and
wings for a monster chess set. But the monster would not
listen and NightMare put the monster into a star-shaped ship
and set it out into space, hoping it would be destroyed.
Fortunately, the monster found itself on a planet full of
beings from around the universe that called themselves Star
Warriors. The Star Warriors took the monster in and taught him
his true nature, sucking things up and copying their
abilities. The monster became obsessed about sword-fighting
and after years of training became Meta Knight. Eventually,
the Star Warriors learned King DeDeDe of Popstar had
connections to NightMare's monster cast and they sent Meta
Knight, who had a experinces and a score to settle with
NightMare to Popstar, where he sword allegiance with DeDeDe to
spy on his activities with NightMare Enterprises. Meta Knight
secretly was in contact with the Star Warriors and they told
him happenings about Popstar and NightMare Enterprises. Back
at NightMare's headquarters, NightMare tired to repeat the
Meta Knight experiment but turning this one pink and naming
him Kirby. But the side effect repeated and NightMare sent him
out into space after only one day of failure and Kirby
crash-landed on Popstar where the anime begins.
Kirby, Meta Knight, and NightMare Theory