It was getting unbearably hot in here. The sauna's heat had been cranked up, and it was affecting even the room outside.
It reminded him of Bismuth's forge.
Steven stared down the teenager before him; the one who'd just busted out of the sauna. The other kids insisted on keeping him behind them, but he was having none of it. He stood before all of them; scared out of his wits but nonetheless ready to protect.
He tried to keep in mind that the guy before him wasn't really Billy. It was the Mind Flayer puppeting his body.
Not-Billy's face twisted in disgust as soon as he laid eyes on Steven.
"WHAT IS THIS?!"
The words boomed in a voice that was both Billy's and... someone-something-else's; something black beyond comprehension; something so vast and so ancient it was beyond Steven's half-Human understanding.
Steven had flinched and covered his ears at the sound, and he saw El almost do the same out of the corner of his eye; before she simply tensed her battle stance. "Hybrid abomination..." the ancient thing wearing Billy growled.
Steven flinched hard at the familiar label; a far-cry from how Peridot; his sweet, lovable friend, had said it all those months ago. "H-how... how do you know... what do you mean?" He asked in desperate confusion.
"Gems can sense each other, halfling," growled Billy.
("Steven! Come on out. You know I can sense you.")
Steven gasped sharply. Behind him, the other teens started murmuring. "W-what? I don't understand! You're a Gem?"
"Foolish whelp," Billy rumbled. "I am no mere Gem. I am the Gem. I am the genesis of Gemkind itself. I am the blackness of space personified. I am Black Diamond."
Steven gasped again. "Black... Diamond?!"
"Yes," Black Diamond said. "B-but how... I-I don't understand. What happened to you? Will said you were a gigantic shadow!"
"DO NOT BE SO FOOLISH AS TO ASSUME THAT IS MY TRUE FORM, HALFLING!"
Steven covered his ears as tears leaked from the corners of his eyes. Every Gem he'd ever met used female pronouns and had feminine voices. This... this sounded like the rumble of primordial thunder; the kind of thunder that rumbled when the Earth was but a volcanic wasteland constantly bombarded with meteors. This sounded like the baritone of an ancient warlord. It sounded like power itself; given voice.
"Such foolishness is to be expected from the mind of a Human. To think, a Diamond is embedded in that filthy meat sack. It sickens me. You bring dishonor even to Pebbles.
Steven's blood ran cold. "Diamond...?" He asked feebly, knees weak and trembling. Billy-Black Diamond-scoffed. "She must be a new one, too. I never saw her in my former lifetime."
"What are you talking about?" Steven shakily demanded.
"Of course; you wouldn't know of me. I'm certain that White did all she could to erase me from history," said Black Diamond, practically spitting the name 'White'.
White...
She must have been another Diamond. Steven had so far only heard of Yellow, Blue, and Pink; in that order. But whenever he saw the insignia of the Great Diamond Authority, there was always a white diamond at the top. Oddly, though, for all he'd learned about the Diamonds so far, White Diamond was never mentioned. She was never even alluded to. Not even by Peridot; Diamond fanatic she used to be.
He'd always figured there was a certain reason White was never mentioned; so he just never asked. But he always wrestled with himself about that. He had pushed about Pink Diamond; about Blue Diamond. Heck, he'd had his recent first and only argument with Garnet about it! He knew about all the baggage surrounding Pink; but he didn't have a problem pushing for answers with her. And yet, White, a Gem whose existence was hinted at only by symbols; one who wasn't steeped in controversy... he'd never asked about her.
Why?
Steven couldn't fully explain it; but he did know why. Every time he looked at the Diamond Insignia; at White's place on it; some unknown surge of fear, like a forgotten childhood nightmare resurfacing, came bubbling up from the very depths of his Gem. In the dead of night, he sometimes wondered...
"Do you remember this place? Do you have any of her memories?"
Pearl had said Gems were like Human computers. A Gem's consciousness, their powers, their appearance... it all was programmed into the stone. Like a crashed software, damaged Gems would reset and come back newer; better; like software updating. Pearl had said that was why the Gem shards from the prototype Cluster experiments only formed certain body parts. Those specific shards held only bits and pieces of the Gem's form's "coding", so to speak. One shard only held arm code, another leg; for example. And in that same way, the Gem's mind was fragmented across the shards as well, because at the end of the day, the Gem's mind was just code.
When they called Corrupted Gems "corrupted", they meant it more literally than one might initially think. They weren't only corrupted in the sense that they had turned evil; they were like corrupted software. The data inside the Gem had been scrambled; rendered completely incoherent. Not fragmented pieces like a shattered Gem, but plasma in a constant state of flux. Not solid, albeit fragmented, pieces, but a scrambled whole.
Gems didn't have DNA the way Humans did. It was all their "code". That was why Steven's mom had had to give up her Gemstone for him. The Gem half of his DNA couldn't be stored in his body like his Human DNA. Because he didn't have Gem DNA; Gems didn't have DNA. They only had coding. Coding that was designed to be held by a Gemstone; not a Human body. Hence, his need for his mother's Gem.
Like any code, system memory was likely stored deep within the layers of his Gem's "coding". Previous versions-previous system memory-was likely stored within, buried beneath the override caused by the Gem changing hands from Rose to Steven, from his Gem updating from Rose to Steven. That was the fear that had plagued Steven recently. If all that was true, his mother was likely still in there; somewhere. He had her memories; even if they weren't surface level programming.
That was his theory. His mom had bad memories of White Diamond; and those buried memories manifested as vague feelings to Steven. Or, considering White's symbol was at the top of the Diamond Insignia, and was what Steven usually thought of when he envisioned a diamond, it could be some kind of base protocol programmed into all Gems to fear White Diamond as Gemkind's supreme ruler; which was why no other Gems dared even imply she existed. Or it could be both.
Either way, the thought of White Diamond alone gave him a feeling of unease so deep he'd describe it as primal; like how Humans naturally feared the dark because of the danger it posed to their ancestors in their dimly-lit caves. To hear someone who called themself (himself?) Black Diamond speak of White Diamond with such hatred; to claim that this feared, unknowable figure had likely feared him so bad she'd tried to erase his name from history...
It made the very silicon composing his Gem shudder and go cold; devoid of the usual warmth and hum of energy constantly pulsating through its intricate quartz networks.
"Allow me to enlighten you; so that you may die with the proper knowledge of who lowered himself to kill an abomination like you," Black Diamond said. Steven flinched violently at the familiar usage of that word.
Abomination.
Accident. Freak of nature.
You were never meant to exist.
They hate you. They wish mom were here instead of you.
"What do you know?! You've never even met-"
"H-hey! I don't know what any of this shit means, but you better stop talking about our friend like th-"
"SILENCE, WHELP!"
Black Diamond's unearthly bellow cut off Mike's defense of Steven. "Do not command me, organic," Black said, spitting 'organic' with more contempt than he had with White's name.
"Now, halfling, listen carefully. I will only recite this story once; and you should enjoy every moment of it. My speaking to you will have given your insignificant, cosmic error of a life a semblance of meaning."
El shifted protectively toward Steven.
"Aeons ago, far longer an amount of time than your pathetic Human brain could grasp, I came into existence from nothing; born from the darkest blackness imaginable: space. I was the most powerful being in the universe. Therefore, I was, and still am, its rightful ruler."
Billy, at Black Diamond's direction, began pacing as he spoke.
"However, I would not stoop so low as to associate directly with lower life-forms; so I created White Diamond, the very image of objective perfection, to rule in my place. Make no mistake; she was not in control. I merely ruled through her. She answered to me. She created the very first Gems; closer to her perfection than the ones Blue and Yellow would go on to create. Perfection lessens the further it gets from the source; you see."
"As the Gem Empire spread across the galaxy, however, White's perfection and illusionary power went to her head. Literally. She thought herself better than I; the original creator. That fool. Thus, she conspired to overthrow me and become Gemkind's ruler. She created two entirely new Diamonds; Blue and Yellow; obviously. She schemed plans to defeat me with her little creations; and, when they presented themselves before me, as they were to do every thousand years, they fused and used their combined power to defeat me. They shattered my Gem; and do you remember how I said they erased my existence from history?"
"I meant it quite literally, halfling."
Steven and the other teens started to involuntarily shiver. Even El trembled a bit.
"They pulverized my shards into pigment and wrote the tale of my defeat with it; and they did it as mockingly as they possibly could. Then they burned the scroll, reducing me even further; reducing me to the smoky excuse for a form I have been trapped in ever since."
Steven's heart skipped a beat as he remembered how the smoke from a burned scroll had once possessed his Together Breakfast. How he'd later learned from Garnet, after they started having to deal with the mutant prototype Cluster Gems, that the scroll had been written with the pigment of crushed Gem Shards; and that Gem pigment lived on as smoke even after it was burned.
"Knowing how powerful cross-Gem fusion was, they told me they were going to ban it under their new 'Great Diamond Authority' so that they would not be overthrown the way I was. They claimed they would not make the same mistakes as me; that they were wiser and more fit to rule Gemkind-to rule the universe-than I was. I, the supreme creator!"
"And can you guess what happens at the end of this tale, hybrid travesty?"
"I-I... uh..."
"They unfused; White personally bubbled my smoky form; and then she SENT ME TO THAT STARS-FORSAKEN ROT DIMENSION TO WITHER FOR THE REST OF ETERNITY; WHILE SHE RULED MY UNIVERSE!"
Steven covered his ears while the other kids cried out in shock and pain at the volume. El's steady, supportive grip on Steven's shoulder suddenly turned crushing.
"And so, halfling," Black began, calm and collected once again; seeming out of breath from his outburst, "That is why I seek to escape that plane and cross over into this world. Because even if my power has been reduced, even if my form has been reduced, I am still the supreme being; no matter what universe I am in. Thus, I am the rightful ruler. And I will rule."
Steven glared as he opened his mouth to tell Black how wrong he was; only to see a hand consumed in a charging blast of dark energy aimed at him and the other kids. Billy's face was polluted by Black's serene (he looked oddly relieved after venting his frustration) smile as he said,
"With that said, halfling, organics, do enjoy your extermination."
Steven hastily summoned a shield just in time for the energy blast to slam into it.
A/N: Yeah, baby. This is my rule for Stranger Things crossovers. Vecna or no Vecna (I don't write Vecna anyway because he's stupid and I don't like to think of him or season 4 as canon) the Mind Flayer can't be just the Mind Flayer. He's gotta be linked in some way to the world of the character who's crossing over into Stranger Things. In this case, the Mind Flayer this time around is an original character; not someone who's actually in Steven Universe. The Demogorgons, like Centipeetle's "children" in Gem Glow, are shadowy (as opposed to normal Gem hard-light) constructs. He has he/him pronouns to establish himself as different (and superior in his mind) than the rest of Gemkind.
It's also to fit with the Yin-Yang themes between Black Diamond and White Diamond. Yeah, I know the male part (Yang) is actually the white part of Yin and Yang; so Black and White Diamond are actually opposites of actual Yin and Yang; but the general idea is still about them being literal opposites; so the theme is still there regardless. They're kind of a perversion of Yin/Yang, to be honest; as the two are meant to be opposite forces yet still work together in a perfect balance; while Black Diamond and White Diamond literally can't stand each other and both think they're the superior force; each wanting to overthrow and become more powerful than the other; being as imbalanced as possible.
The idea of Black Diamond was inspired by old theories from the fandom; theories from years ago. For some reason, hearing them theorize about Black Diamond on Crystal Clear (by The Roundtable) stuck with me for years. In the green hand ship, the Era 2 Diamond Insignia (the updated one they made after Pink Diamond's "death" which doesn't include Pink) on the floor forms a dark triangle between White, Yellow, and Blue Diamond where they meet at the center of the insignia. Some have theorized it means their fusion would be Black Diamond (a cool parallel to how the Crystal Gems' fusion also forms a black Gem, obsidian) but I rolled with something different for this fic, lol. The idea of Black Diamond forming from the depths of space itself is a nod to the fact that, in real life, Black Diamond isn't found on Earth. We've only ever gotten it from space; like from meteorites and stuff. The black stone comes from the infinite black depths. Fitting, right?
Anyway, enough of my rambling. I hope you enjoyed, and as Steven would say...
Have a great weekend!