Moonstone

Moonstone had a highly-respected, almost religious role in society before he was sent to Nacre. He was paired with his Sunstone after leaving his Kindergarten and spent the next few thousand years as her constant companion.

They were tasked with protecting their assigned planet, moon, or outpost from the natural disasters that might threaten them. Their services weren't always necessary, but having them there put the other gems at ease. They'd also counsel the gems in their care on personal or other problems. Sometimes they were one of many pairs of Sunstones and Moonstones, other times they were the only one's there, but through all of it they were together. They were never apart. Fusing was a forbidden thing for them, but if it hadn't been, they would have fused once and never gone back.

But something changed. Rebels cropped up around the gem empire and he couldn't...he just couldn't anymore. What the empire was doing was wrong. He'd watched planets die under his feet, trillions of lives lost for what? A pretty new planet for the Diamonds? Moonstone kept these thoughts to himself until he was faced with a dilemma: a gem at the colony he was presiding over came to him for advice. Did he promise he wouldn't turn her in? Of course. That was always the promise. He and Sunstone were patient and listened without hanging the threat of death or imprisonment over their gems' heads. That's what they'd always agreed to.

She was a rebel. She was close to discovery. She had nowhere left to go.

He couldn't do nothing.

She was the first of many he smuggled to safety. He fed them information to keep them safe and help them fight the Authority. Moonstone was too highly-valued to be under suspicion and he did his best to cover his tracks.

It didn't matter. He was found out eventually. All the respect he'd cultivated with the other gems over the decades and centuries crumbled when they found out.

The trial was a formality. He admitted to everything and spat the truth right in the Diamonds' faces: they were evil, cruel, selfish brutes who sucked the life out of every planet they could find with no regard for other forms of life. How dare they commit repeated mass genocide because they wanted something shiny and new.

It sickened him that his death would hurt his Sunstone. No. Not hurt. Destory. And he had no time to apologize, no time to beg for her to keep going and train up a new, younger Moonstone who wouldn't do this to her.

But that's not what happened. She pleaded for him. Of course she did. And that was when they sent him here, to Nacre. 

She looked soft and gentle like his Sunstone, but if she still had her eyes he knew he'd see ice in them. The agreement was that she wasn't to kill him unless absolutely necessary, but that only inspired her to rise to the challenge. Nacre cracked him and patched him over and over and over. She grafted shards into the chinks she formed and coated his gem in her pearlescent ichor while he was awake and formed and aware. Moonstone had never thought about what it would be like to have awareness while your gem formed--it was horrifying. Every time she did it, Nacre broke his mind a little more.

Moonstone still has his prime memories. He knows who he was--is--in spite of the conflicting thoughts in his head. He's had gem shards shoved into him and yanked out so many times it's hard for him to remember how many gems he's been. The tender nature that made him side with the rebels in the first place made this experience even more torturous: so many of the shards came from rebels and off-colors who were murdered for being different. It took centuries, but Nacre broke him.

He's kept heavily restrained at all times for good reason. Moonstone--or whatever he is now--has a wild, dark edge to him. He ate Nacre's pearl once. Just...ate her. She poofed him but never found the pearl's gem. He laughed for days afterward, crawling on all fours (sixes? his number of appendages changes whenever he gets a new crack or graft) and snarling at every pearl who passed his cell. If his hands or mouth(s) ever get free, he crushes all gems within reach and hides, shattering every gem who gets too close. Thankfully, he's never gotten past the prison and it's been decades since his last escape.

Most gems don't know he's there, but the pearls bring him birds and plants to decorate his cell with at Sister Sunstone's request. They've been ordered never to speak of him outside of the prison.

He calls Powder Rose "Angel" and has threatened to eat her more than once. She is very good at pretending not to be scared.