(This takes place before Steven's existence/birth. So, Rose Quartz era. Also this is a small Crossover with Undertale and Naruto. The Undertale characters will never actually appear, just Undertale like powers for Ryuuto. The Naruto part is the same, just referenced due to Ryuuto's bloodline.)

(DISCLAIMER: I OWN NOTHING EXCEPT A PC AND A I-PHONE.)

1. The Beginning.

Beep…

Beep…

Beep…

Those were the sounds of a heart monitor. On a bed next to it, was the young 300-year-old Demigod of Peace, Ryuuto Otsutsuki-Shock. He looked fairly young, barely 17; which couldn't be farther from the truth.

Thing was, Ryuuto was dying. He was dying from a fatal disease that ran through his father's side of the family, that affected the heart.

Next to the bed, were two people. One was Gaster, the one lost to the Void and unable to get home. The other was Ink Sans, Ryuuto's adoptive uncle. They were worried for the young Demigod's life.

"Ink, there has to be something we can do!" Gaster worriedly said to the Creator.

Ink was silent. "There is one thing we can do, but it's risky."

"What is it…" Gaster's eyes widened then. "No, we aren't sending him to that world!"

"Once he goes there, his new ability will cancel out the disease! Gaster, it's for his own good! Besides…" Ink smiled. "Ryuuto loves to help anyone in need."

Gaster sighed. "Fine, he'll be sent there and I'll give him a Gem." Gaster fused a gem (specifically a white emerald) into Ryuuto's body, which soon turned a dark grey. "He'll be known now as Grey Emerald."

Ink opened a portal to that universe and smiled. "Then let's send him off! We want him to be saved as soon as possible."

Both powerful beings picked up Ryuuto, who woke up from his slumber and helped him walk into the portal. They were now standing within a beach. "Ryuuto, this place is in need of your help. That Emerald gem of yours will act as a stabilizer for your body, boosting your immune system. Stay here long enough, and the Gem's power will eradicate the heart disease."

Ryuuto weakly nodded, using his jacket to cover up the Emerald on his chest. "Thanks, Uncle Ink. Thanks, Uncle Gaster." He said, walking away to Beach City's inner city.

He was getting a few odd looks, and Ryuuto knew why. It wasn't every day someone walks into Beach City with white-red hair, heterochromatic eyes, and a small scar on their cheek.

As he was walking around, he noticed something. Some strange creature that was terrorizing and attacking some citizens. Ryuuto rushed at it, kicking it to the side. "Oi, you people run to safety. I'll deal with this."

The people nodded fearfully, running off and saying thanks. Ryuuto looked to the creature, seeing it closer up. It was a centipede-like creature, colored green, with jaws opened wide: hissing at Ryuuto. Within the jaws was a green eye. "You are terrifying."

The Centipeetle jumped at Ryuuto, who ducked at the last second, punching upwards. The Centipeetle was knocked away, and it hissed at the Demigod-Gem hybrid again.

Ryuuto summoned his Determination Blade, slicing at the creature and poofing it. He stared, letting his sword fade.

...Only to summon a shield to block a spear aimed for his head. Ryuuto turned, jumping back to gain distance. "Yikes, that would have been unpleasant."

"What are you doing here Gem?!" A frantic voice stated. Ryuuto was now facing the Crystal Gems.

Rose Quartz, the leader of the rebellion.

Garnet, the strong and wise fighter.

And Pearl, the calm and patient second-in-command.

'Wait, how do I know that information?' Ryuuto thought.

"Ink and Gaster stuffed information into your head, Gaki. So you don't die from stupidity."

'Oh…'

"Hey, I'm talking to you!" Pearl growled, striking at his shield again.

Ryuuto blinked. "Sorry, internal conversation. First off, I'm not a Gem. At least, not naturally."

Pearl and Garnet were confused. But Rose Quartz was intrigued. "Not a Gem naturally? How so?"

"Well… I… I'd be dead soon without my Gem." He showed them his grey Emerald, which was resting on his chest. "I was infected by a family disease, called the Soul Leech. The only way my guardians saw for me to live was to give me a Gem and send me to learn how to control my Gem abilities."

Everyone looked sympathetic, which annoyed Ryuuto a little. "Poor you, a young human child…" Rose Quartz began.

"One, not entirely human. Two, I'm over 300 years old. In fact, I am 356 years and 23 days old." That caused even Rose to be confused.

"Child, no human can live for that long… they all fade away so quickly…"

"I used to be an 'Immortal' Demigod. I can live up to 6,000 years old at least. At most 180,000." He grunted. "In fact, for proof…"

"No proof will be necessary. I saw how you defeated that Corrupted Gem. No normal human would be able to do that, and I didn't see you activate your Gem." Rose smiled.

"...Oh, where are our manners? I'm Pearl." Pearl began.

"Garnet." The stoic warrior said.

"And I am Rose Quartz, leader of the Crystal Gems."

Ryuuto nodded. "I'm Ryuuto Otsutsuki-Shock, Demigod of Peace… and now the wielder of the Grey Emerald gem."

Rose shook her head. "I still can't believe there really were such things as Grey Emeralds."

Ryuuto was curious now. "What do you mean Rose?"

"Not here, first we have to bubble up the Corrupted Gem." She did so immediately and began to walk away with her group. Ryuuto stood there, confused. Rose turned back to the Demigod. "Aren't you coming? You wanted answers and training, it's best to come with us."

Ryuuto shrugged and followed the Crystal Gems. 'What could possibly go wrong?' He thought.

(With Gaster and Ink)

Ink was watching Ryuuto's progress until he saw the timeline deviate from what it was meant to be.

"Uh, Gaster? Is it good or bad that Rose finds Ryuuto cute?"

"...I don't know, what do you mean?" Gaster, still being a goopman, slid over to Ink, and saw what Ink was seeing. "Oh… oh dear, that's a massive change…"

"But Steven will be stronger that way. Besides, Apophis never liked the Gems. He'll try and eradicate them, especially since Ryuuto is there."

"True." Gaster relented. "We just have to leave it to Lady Fate."

(Back with Ryuuto and the Crystal Gems…)

"...So you're saying, that a long time ago… the Grey Emeralds were the Diamonds best friends and advisors?"

Rose nodded.

"And since I am a Grey Emerald, they'll come after me?"

Another nod.

"And my only chances of not being captured is staying here with you guys on Beach City."

A third nod.

Ryuuto slumped into his chair. "Well that's just great, I have more intergalactic warlords after me." He groaned. "First my own grandfather, according to Alpha's words, and now the Diamonds once they hear of me."

"Alpha…?" Pearl asked inquisitively.

"There are different worlds with different versions of me. The Alpha is the strongest, the King of all Ryuutos."

The 3 Crystal Gems blinked, having to take in that information properly.

"I can tell you're confused… and for good reason too, because even I had trouble understanding this until a few weeks ago." Ryuuto shrugged.

"So, how strong are you anyways?" Garnet asked.

"Pretty strong, you could say…" Ryuuto shrugged. "I mean, I did defeat that Corrupted Gem. I'm pretty formidable."

Rose looked at Pearl and Garnet and then nodded. "Ryuuto, we have a mission for you."

(Later that day)

Ryuuto was facing down a bunch of Centipeetles, dodging attacks from them left and right. One got close to injuring him badly, but he punched it in the jaw at the last second, kicking it to the floor with enough force to poof it.

They tried to outnumber him, but he put a barrier around himself. Then threw the barrier outwards, knocking them all back. He jumped into the air, sparkling energy forming in his hands. "Lightning Collapse!" He shot the white lightning blast at the Corrupted Gems, poofing them all immediately and saving the village they were torturing. "All done…" He grinned.

He turned to the Crystal Gems, waiting for some praise, but only got shocked and slightly terrified looks in return. "What? Did I do something wrong?"

Rose stared behind him, and Ryuuto turned to see what the others were seeing. A giant dark orange blob, easily towering over the trees. He knew what that was. A footsoldier of Apophis.

"Guys, run!" He ordered, making Shadow Clones to distract the blob-monster. The blob raised a dark orange slimy tentacle-arm to swipe at the Clones, poofing some of them into smoke.

"Where are we going, those humans are going to get hurt by the creature!" Rose frantically asked the Demigod-Gem.

"I'm just a clone," revealed the Ryuuto clone. "Boss is dealing with the blob on his own, only he can defeat it."

Ryuuto faced down the blob, slicing at it with his sword. Bits and pieces of it fell down and tried to kill Ryuuto, but he dodged to the side, throwing fireballs at them.

Ryuuto stared at the blob, raising a hand and summoning a Gaster Blaster. This one looked different though, with an Emerald gem in its left eye. It shot a green beam at the blob, with Ryuuto summoning 10 floating hands.

The floating hands were based off of Gaster's, but these had white Emerald gems in the middle of them. The Emeralds turned red as they shot red beams at the blob, causing it to hiss and roar in pain as pieces of it dissolved. "All right, citizens. I need you all to evacuate!" He ordered. The humans in the village nodded and ran off quickly.

Ryuuto glared at the beast, raising his hand as a sphere of red energy formed. It spiraled and shifted, with blade-like parts extending from it. "To finish you off, Fearbringer, I'll use this! Blood Style: Crimson Rasenshuriken!" He kicked the Fearbringer into the air, and then tossed the attack at the blob. The Crimson Rasenshuriken blew up and destroyed the Fearbringer entirely.

"That was amazing!" Ryuuto turned to see Rose Quartz staring at him with awe. "You possess such power and at only 356 years old?" She asked, with the other Gems staring dumbly in shock and awe.

"I've been training, aiming to get stronger since I was a child." He shrugged. "I got somewhere from it."

The Gems grinned at Ryuuto (sans Pearl, who stayed stoic). "You'll fit in nicely, Ryuuto. Welcome to the Crystal Gems."