Seeing constellations got me thinking of a similar but very different story that if like to hear your thoughts on (and maybe see you bring to life).
Y/n was a gem that served the Diamonds but one day rebelled. As punishment they tried to destroy him but somehow his gem was instead perfectly split in to two fully functional gems that contained half of his personality. One half the seemingly obedient and angry warrior the Diamonds would call Orion, the other was the kinder side of him that chose to rebel for the sake of others, the Diamonds would call him Sirius.
Sirius alone would escape, choosing to call himself Y/n. Whenever the two halves meet they ultimately fight due to various reasons which become deeper rooted with every fight.
Eventually Y/n crash lands on Earth and meets the crystal gems. Story begins.
P. S. Orion would refer to Y/n as Sirius out of spite and because he doesn't believe that either of them are worthy to have the name of their original self.