Kai

 Diamond Gem hybrid .

Is pretty much isolated,  since everyone  fears his lineage and  mabes smothering/gatekeeping  ,   rarely anyone befriends him apart from his moms leftover court  and strudel the brown diamond  ,who took a liking to him due to being quite similar to him as a kid . 

His mom left a pearl behind so hed stay safe 

He was raised spoiled rotten with the idea that hed grow up to act   privileged , manipulative  and better than the rest - traits of a fine diamond . It worked at first , until he grew up and started  interacting with the world, after that it went all downhill from there (at least from mabes perspective.)

hes curious, rebellious, and likes to annoy mabe pearl.  

he runs the gem/human archival and assistance systems on earth - he loves helping a hybrid rediscover their history and help them find their purpose