His Corrupted Self Summary: When Spinel attacked his planet, she didn't bring just a rejuvenator but a corruptor as well. He knew she wanted vengeance against his mom. He didn't know she would slash him with the rejuvenator before ripping his gem free and slashing that with the corruptor. Steven is split in two and his gem half doesn't look right. For one, it's red and not pink. For two, it's gained sentience different from his human half. And not the good kind of sentience either. Now Steven is fully human and fighting not just against a rogue gem, but his corrupted self as well.

Notes – This is a Steven x Corrupted Pink!Steven story. Steven-cest. Had an idea, thought it was fun, and ran with it. I'm calling this the Red Diamond AU.

WARNINGS – Self-cest, Steven-cest, yandere, NSFW non-consensual sex, molestation, corruption, dark themes, violence, collars, forced submission, Steven suffers, angst, physical abuse, emotional abuse, sexual abuse!

His Corrupted Self Part 1

Sweat pooled down the base of his neck. Pain rippled throughout his body and blackness spotted his vision. His weight was too heavy, gravity keeping him pinned to the grass. He panted, blinking fast as the world seemed to topple over itself. Grass. Sky. Something pink and massive and drilled into the ground. Dizziness buzzed in the back of his brain. He struggled to right himself. A brilliant red light flashed. Someone shouted near him but the voice was muffled by the ringing in his ears.

"Please…" he wheezed and the person helped him upright. More shouts became clear. "Please…"

"Steven," urgency layered the familiar voice with tension. "Steven, we need to go."

"Wha?" Rich purple-pink limbs hefted him up. Garnet? He struggled to breathe. "Garnet…?"

"Yes, it's me." Red flashed again. Someone screamed. Blearily, he tried to look. "C'mon."

He curled into her hold. The ringing slowly settled but his heart rate didn't. Garnet ran forwards and he took a moment to remember where they were. The cliff beside Beach City. The grass by the lighthouse. Spinel. The injector. Two cracking scythes. His gem ripped clean out of him. He jolted. His gem! He fumbled for his blue shirt, pink jacket bunching with the movement. Shaking fingers shifted fabric and checked skin. Bare skin.

"My gem!" He gasped. "Where's my gem?"

"No time." Garnet shifted her hold on him as she crouched to pick something off the ground. Then she was running again. "Pearl!"

"Right!" Came a familiar response and Pearl appeared beside Garnet.

"Amethyst?" He cried. "What about–?"

Garnet's palm opened just enough for him to spot a purple gem. A cracked purple gem. He flinched. What happened?

"Hey!" A high pitched voice yelled behind them followed by a grunt. "I'm not your enemy! They are! Whoa whoa! Do I look like I have him to you?"

Red darkened the sky. Steven leaned into Garnet's torso as he tried to peer around her. Spinel was fighting someone. But who? His jaw dropped. Red. A figure colored in red light shot red discs at the one who had attacked his planet. The attacks cratered the grass. He squirmed. Strange. The figure looked familiar. Almost like… The figure turned and caught his gaze. His jaw dropped.

"That's me…" he breathed. "Wait! Garnet, that's my–"

"Something's wrong with it!" Pearl cut him off as they ran. "Spinel, she–she hit your gem with a corruptor!"

"A what?" He tried to move but his limbs felt so heavy. The red lookalike, expression blank and eerie, started to walk towards them. "What? That's my gem half! I need–"

"To get away." Garnet corrected. "Whatever that thing did to your gem changed it, Steven. That's not… that's not your other half right now."

"But!" He cried and gestured at the red figure of himself. The figure's head tilted slightly as it continued to follow. "But how? And–and the injector! What about the injector?"

"Not important." Garnet answered. "We need to get you to safety."

"He'll die no matter what!" Spinel fell into step beside them. Garnet swerved away from her and she cackled. "My injector will kill all organic life and only I can stop it." She shot them a wild grin. "I win!"

"Wait!" Steven reached for her as she bounced a step away. "Stop! Come back!"

"And get fried by Red over there? Don't think so!"

With that, she fled in the other direction. A panicked whine escaped his throat. He looked to Garnet and Pearl, both still running towards Little Homeworld. He tugged on the gem and shouted over the whistling wind.

"We have to go after her!"

Pearl shook her head. "Not now."

"We need her!" He looked to her retreating back. "Spinel!"

His gaze shifted onto his red lookalike. They were too far to meet eyes but dread swooped through his stomach. His gem half raised an arm towards them and a warped version of his shield materialized and shot towards them.

"Guys!" He screamed. "Watch out!"

Garnet tackled Pearl out of the way, Steven curled in her hold. The red disc shattered upon impact with the ground and the ground itself erupted. Dirt billowed and rocks scattered fast in every direction. Steven stared at the resulting crater from his safe spot between the gems. That… that wasn't… How much power did his gem self have? He coughed as dust caught in his throat.

Garnet handed him and Amethyst's cracked gem to Pearl as they stood. "Run, I'll try to hold him off."

Steven reached for her. "Wait, Garnet–"

"Understood." Pearl nodded, tone somber. Her expression was grim.

Steven tried to protest but then Pearl was running. He tried to struggle but he was weakened and Pearl was not. She ran even as a distinct poof resounded behind them. He peered around Pearl just in time to see the stranger with his own face pick up two gems. When had he neared them?

"Don't hurt them!" He cried. "Please!"

The lookalike, Red, met his gaze with an unreadable stare. The gem half pocketed the gems and continued to approach. Steven's heart hammered. Somehow, the gem moved fast without even needing to run. Like each step was boosted with power. He gasped when the gem raised a hand and another shield materialized. He squirmed, desperate to summon a bubble to protect them but nothing happened. No power. No hum of energy. Nothing. Then the shield was whizzing towards them and he could do nothing but scream.

"Pearl!"

She was too slow. The weapon too fast. The disc's razor edged sliced clean through her head and nose, narrowly missing her gem. Her wide eyes met his own as she vanished and he fell. He thudded to the ground. Her gem bounced off his back and rolled onto the grass. He struggled to right himself as he swept the Amethyst's gem and Pearl's gem into his arms.

Red feet neared his face and he craned his neck to look at his attacker. His other half. Himself. But was this stranger really him anymore? The lookalike stared him down before reaching.

"W–wait!" He tried to backpedal but he had no strength. He collapsed, boneless.

Red hesitated. Just a beat. Then grabbed him by the wrist: under the fabric and directly touching his bare skin. The contact burned. He yelped and tried to pull away but the stranger held tight.

"...mine." A distorted voice, like a machine that had glitched and only worked in fragmented pieces, came from the stranger. His reflection warped and seemed to morph into sharper edges. More angular. And his pupils? Diamonds. Red diamonds for eyes.

Steven swallowed as the other held him in place. "...who are you?"

The other shrugged; just a slight movement of the shoulders. "Different. Someone new." The grip tightened. "Just need you. Only you."

"Wh–wha?" He tried to pull away but was pulled up and into the stranger's arms. "Wait–wait!"

Red stared him down. Cold. Blank. Unfeeling. He shuddered and curled tighter around the pale white and purple gems in his hold. "...you poofed them."

"Yes." The stranger started to walk to the lighthouse, carrying him bridal-style.

"Give me Ruby and Sapphire."

"Who?"

"What do you mean–? Garnet! The gem! The gem you poofed and they split in two! I saw you grab them."

Red stopped to stare before narrowing his gaze. "...they are not important." His gaze flicked to the two gems clutched against Steven's heart. "Neither are they."

Steven bristled. "What? Of course they are! They're my family. Our family."

The stranger's lip curled and it was strange to see such a cruel expression on a face so similar to his own. "Don't need them. Only me."

"Now I know you can't be me." Steven squirmed, fumbling for the reflection's jacket as he started to walk again. "Cause then you would know just how important they are. Now give them back so I can fix this mess."

"No."

"Yes." He glared. Shoot. Not in the nearest pocket. "First, I need to make sure they're safe. Then find Spinel so she can stop the injector. And then figure out what's wrong with you so everything can go back to normal."

"Nothing wrong." The grip shifted, preventing him from reaching the other pocket. "I am me."

"What?" He tried to free the limb not pressed against the red chest. The stranger had a firm hold on his upper arm. "No. Everything is wrong. You're not right. You're not even me right now."

"Not you." The distorted voice glitched and smoothed into a lower register. "I am me."

"No, you're–"

"I am me." The other insisted. "Not you."

Steven huffed. "Yeah? And just who are you if you're not me?"

The other neared the lighthouse. He checked behind him, glancing briefly at the injector, before facing the cliff face. Below them, the endless sea stretched. Closer than that was the statue of Obsidian carved into the rocks. Within one of her palms sat his house.

"Hey!" Steven wiggled. "Answer me."

Red irises shifted from studying the house to piercing him with a blank stare. Slowly, the pupils dilated into large diamonds. Lips curled into a lopsided smirk. It was unsettling to see such a dark expression. On a sharper version of own face no less. Steven leaned away.

"Red Diamond." The stranger cocked his head. "I am Red Diamond."

And then he jumped.

Steven screamed as they tore through the air. He scrabbled for purchase. He was powerless and freefalling. He could die. Only once they neared the balcony did the stranger kickstart the powers and defied gravity. They slowed their ascent and alighted upon the wood. Steven's chest heaved. They stood in front of the door.

"Why would you do that? We could've–we could've died!"

"No." The gem turned the knob. "I have you. You are safe."

Steven spluttered. "That doesn't–Look, uh, Red. We have stuff to do! We need to find Spinel–"

"No."

Steven flinched as Red actually growled. Still, he persisted. "We have to! Everything will die if we don't."

Red hummed. He opened the door and stepped inside. A quick look around pulled his features into a frown. "...you live here."

"Yes, now can we please focus?" Steven squirmed but he was still weak.

"No, no." The Diamond pivoted and walked out the house. "This won't work."

"What?" Steven groaned as Red scanned the beach. "C'mon, Red, we gotta stop the injector!"

"Need the best." The other muttered. "Have to build?"

"Red!" Steven reached up to tap a shoulder. "C'mon!"

The Diamond ignored him. "Injector doesn't matter. Only you."

"Yeah? Well I'll die too if we don't stop the injector."

Red finally focused on him and not with just a passing glance. The sudden intensity and full focus of the diamond stare prompted him to shrink. "You'll die?"

"Y–yeah…" he swallowed and patted his stomach. "The injector will kill all organics. And I'm an organic. Half human, you know?"

A flicker of fear flashed in the other's eyes. "Can't die." The expression hardened with grim resolution. "Won't die. You're mine."

"I'm… gonna worry about that bit later. For now, we need to stop the injector!"

"Will destroy it."

"No no!" He waved his hands. "No, Red, that'll just spill bio poison everywhere. We need Spinel."

"Gem left." Red grumbled.

"Then we gotta find her."

A frustrated huff and jump atop the injector itself later, they scanned the area. Steven couldn't see anything from the distance but apparently Red could. In short order Red had spotted the gem, hunted her down, and bubbled her entire body before she could react. Steven could only clutch the gems in his hold as the Diamond half of him ruthlessly hurled her, bubble and all, back to the injector. She yelled the entire way. Before Steven could protest such harsh treatment, they were back at the drill site. She sneered at them from inside the red bubble.

Steven opened his mouth but Red spoke first. "Turn off injector."

"No." She snarled. "You ruined me. So you pay the price."

"I did not!" Steven argued back. "Mom was the one who hurt you. Not me. Please, we can talk this out."

Red added. "Turn off injector."

"You're cracked."

"Turn off injector."

"Your gem is a broken record." Spinel cackled before she lunged against the bubble's surface. "Hey, hey. Won't it be fun to watch your human half die?"

Something changed. Steven didn't know what happened. One second the grip around him was tight but harmless and Spinel was laughing wildly. The next it was crushing and Spinel looked terrified.

"What...are you?" She squeaked.

Steven faced his other half and balked. Scales. His other half had scales sprouting across his features. Horns curved up and outwards from his forehead. His teeth sharpened to lethal points, jaw widening to accommodate. He looked like some sort of monster. Or–or some kind of fairytale dragon.

"Corruption." Steven breathed. His other half really had been corrupted. But how? With the 'corruptor'? What did the corruptor even do?

"My name." Hisses and whistles echoed as the mouth moved with the words. "Is Red Diamond."

"Alright, alright, yeesh!" She tried to dismiss him, clearly struggling to hide her unease.

"You will turn off the injector." Vibration rolled around Steven as an aura of red glowed. "That's an order."

A shudder rolled through Spinel as pink limbs snapped into a diamond shape. "Yes, My Diamond."

The bubble popped. Steven gawked. With a lowered gaze, she formed a horn with her pinky and blew hard. The noise reverberated in his ears and the ground shook as the drill pulled itself out of the earth and returned to the sky. It hovered there. Threatening and yet harmless all the same. Her gaze stayed low as she resumed her salute.

"Wha...what did you do to her?" Steven tried to pull out of the hold, uneasy.

"Gems obey diamonds." Red said as if that explained everything. "Spinel."

Despite the low gaze, her expression was sour. "Yes, My Diamond?"

"Where is my palace?"

She frowned. "Palace?"

Steven echoed her. "...you don't have a palace, Red."

"Build one." Red zeroed on her. "Need one. For him. Where are my gems?"

Steven twisted to stare at the stranger's face. The draconic features had faded, leaving nothing but the fangs protruding over his bottom lip. Steven frowned. What was happening to his gem? He flexed his fingers, testing if they still felt like jello.

"Red, you don't need a palace." He checked the crack in Amethyst's gem. "But we do need to heal Amethyst."

"Not mine. Your palace."

A quick lick to his palm and tapping the gem proved nothing. He sighed. "I don't need a palace. Can you heal her?"

Red checked the gem and scrunched his face. "Why?" He refocused on the gem in front of them, gaze aglow. "Spinel. Follow."

She squawked but obeyed without protest. Steven squirmed, uncomfortable. "Red, stop. We need to heal Amethyst. Put me down, okay?"

"No." The gem continued to walk along the grass. "Where are my gems?"

"You don't have anyone."

"I am Red Diamond."

Steven dragged a palm down his face. "No, you're some twisted, messed up version of me and we really need to fix you before we re-fuse. That, and fix Amethyst. Preferably before she reforms."

Red finally seemed to think for a moment as they walked to the shoreline. "Fine. Will fix her. Cracked gems are useless otherwise."

Steven scowled. "Don't say that! Cracked or not, every gem is important. How can you be a part of me if you think like that?"

"Not you." The other mirrored the expression. "Red Diamond."

Steven groaned. Red continued along the beach, Spinel quiet behind them. "Not this again. Look, I know you're corrupted and all but that's not how the world works."

Red jostled him. Someone shouted in the distance and Steven shifted to see Bismuth, Lapis, and Peridot running or flying their way towards them. He brightened.

"Guys!"

"Steven!" They called in return.

A dark red shield materialized in front of them. Up close, Steven had a chance to see the pattern was more of a draconic snake than a rose with a vine of thorns. He frowned. Why did Red throw up a shield? Clearly the three gems were startled by it too as they slowed to a halt.

"Steven, who are they?" Lapis' wings flared dangerously.

Peridot punched a fist into the air. "And why's he look like you?"

"Uh…" Steven fumbled for an explanation.

Red tightened his grip and glared at the three gems. A beat passed before the grip loosened and the shield lowered slightly. Just enough for the gems to see the Diamond's gaze.

"State your names and purpose." A red aura glowed.

The gems gasped as their bodies straightened out of battle stances and into diamond salutes. Bismuth clearly tried to fight whatever power was running through her but she dipped into a bow. Lapis' wings evaporated and she landed on the sand with a grunt and bow. Steven gaped as Peridot spoke first with a scrunched face.

"Peridot, resident of planet earth: friend and ally of Steven Universe. Currently helping complete Little Homeworld to further home other gems of planet earth."

Red seemed to perk. Lapis pitched in. "Lapis Lazuli, resident of planet earth: friend and ally of Steven Universe. Currently a builder of Little Homeworld. Assistant to Peridot and Bismuth."

Bismuth added. "Bismuth, resident of planet earth: friend and ally of Steven Universe. Currently the blacksmith and builder for Little Homeworld."

With their speeches complete, they straightened but kept the salute. Steven started, dumbstruck. "What did you–?" Mental gears click. "Red, you need to stop! Stop using your diamond powers, it's not right!"

"They are mine." Red dissolved the shield. "As are you."

"What? No! You don't own anyone! This isn't right! Stop it!"

Red kept a solid grip on his struggling form. They approached the three gems and Red met their sour expressions with one of his own.

"Where are the other gems?"

Peridot shot back. "Where are our friends?" Red merely darkened his gaze and Peridot jolted as if he had zapped her. "Other gems are located in Little Homeworld."

"Good." Red sneered and his eyes glowed once more. "You three. Follow."

Though they tried to resist, they fell into step behind him. Steven squirmed, struggling to peer around him to look at them. He clutched the two gems in his own hold like a lifeline and leaned across Red's upper arm. The four gems trudged behind them. Lapis' teeth were gritted as she grabbed her own elbows. Bismuth was furious with swinging fists at her sides. Peridot made her displeasure known with stomps. And Spinel watched the back of Red's head with a wary, tense frown. Steven caught their gazes with an apologetic one of his own.

"Red, this is nuts." He wiggled. "You need to stop this and stop it now. Can't you see you're hurting them?"

"They are my gems." Red jolsted him back into place. "Gems obey Diamonds."

Peridot gasped behind them. Steven reached up and smacked his shoulder. "That stopped years ago. So cut it out and let us figure out how to fix you."

Diamond pupils narrowed focus onto him and he swallowed. The red irises glowed in silent warning. The Diamond spoke, enunciating clearly and coldly. "I am Red Diamond. I am not broken. You are mine."

A shiver rolled through him. "St–stop saying that! It's creepy."

"It's the truth." Red answered. "You belong to me. Only me. My gems will build you a palace. We will rule this planet. Together."

Dread swooped through him. "Wh–what…?"

With the fear came silence. Steven simmered in his thoughts as they approached Little Homeworld. What could he do? What was he supposed to do? His other half had either completely lost it or was genuinely someone new. Someone different but shared his face. A new gem. A new Diamond. No, not just a Diamond. A corrupted diamond.

They arrived on the outskirts and were greeted by friendly albeit puzzled gems. Steven swallowed, struggling to think of something to say, when Red spoke. His voice was cold but authoritative. Light glowed and Steven gasped, lurching in the hold.

"You will build a palace." The Diamond commanded, forcing any gem within earshot to comply. "And you will build it now. Anyone who isn't working should be brought to me. Dismissed."

The gems scrambled to obey. Steven made a noise akin to a wounded animal as Red Diamond pivoted to face the rest of the Crystal Gems and Spinel. "Red, please–"

"My other half needs to rest. You three: guard him while I work. Ensure no one touches him or I will shatter you. Spinel, with me. Understand?"

Steven gasped as the four gems straightened into Diamond salutes, echoing one another. "Yes, My Diamond."

"Red, please, wait!" He struggled as his other half led them into an empty house. A quick check proved there were no threats in the living room, bedroom, or kitchen. Steven cried out as Red deposited him gently to the living room couch. "Red, stop! This isn't right! Stop controlling everyone!"

Fingers threaded through his hair and lips pressed against his temple. He froze as Red murmured. "I will return. Stay here with your soldiers."

"They're not soldiers!" He grabbed the wrist pulling away from his hair. "They're my friends."

The Diamond smiled at him, like he was an innocent child rather than a young adult. The visible condescension churned his stomach. Fingers reached for the two gems in his hold and pried them free.

"Stop!" Steven lunged for Pearl and Amethyst but Red kept him away by his hair. "Give them back!"

Red crooned gently, the melody soft and soothing and so at odds with the rising tension. "Hey now. You're okay. I've got you. You're mine, Steven."

Steven recoiled as if he'd been slapped. His gem half had never–had never called him by name before. And it felt wrong. He wasn't supposed to be someone else. He was supposed to be whole. Not ripped into two different people. But it was odd. He felt the same as when he was one being, only weaker. But his gem half was clearly different. Clearly wrong. And clearly not like him at all.

He flailed in place. "Give them back!"

"They aren't trained." Red soothed. "They might take you away again."

"They're my family!" He wrenched focus from the poofed gems in Red's hold to the still standing ones. "Bismuth, Lapis, Peridot, help me out here!"

Their face scrunched and their bodies tensed. They trembled in place. Slowly, Bismuth managed to approach and Steven watched with an open mouth as she halted before them. Her arm started to move up, reaching for where Red held him by the hair, but only curled into a fist instead and it dropped by her side.

"I'm sorry, Steven." Bismuth drooped.

"Wha…?" Steven studied her tight expression. He whipped onto Red. "What did you do?"

Red cocked a brow. "Gems are made to obey Diamonds."

"Stop. Just stop it!" Steven reached to untangle the fingers in his curls. "This isn't right. Red, please!"

The Diamond pulled away and Steven took a moment to realize small horns had started to grow once more at the line dividing his hair and forehead. Steven swallowed. It was getting worse.

"We can still fix this!" He stood as Red turned away, gems stuffed into his jacket pocket. Absently, he reached for Bismuth's hand but she jerked away. His jaw dropped. "...Bismuth?"

She dipped her head as Red cast them a cool glance. "Diamond's orders. If she or anyone touches you, I'll shatter them."

Steven gasped, horrified. "Red, you can't do this."

"I can." The Diamond shrugged. "I have."

"Red, wait, stop!" He scrambled as the other opened the door. "Stop!"

Lapis blocked his way, expression pained. Steven resisted the urge to shove her aside. Red cast him one last lingering glance.

"I'll be back, little dove."

And the door shut behind him.

Notes: Ah, yes. Betcha didn't expect something like THIS! Anyway, this is basically a self-indulgent Steven-cest AU. Stevinel will prolly also happen here. Gotta have my yandere in any and all forms. If you made it all the way here, then you must either be curious or just a kinky lil thing like me. Ha ha!

Thanks for reading my Red Diamond AU! Feel free to share your thoughts.