The Earth, 5,750 years ago.
It was a promising site of a new Pokémon colony, but progress was being thwarted by a small, persistent group of rebels. A team of diplomatic Pokémon was sent from their home world to investigate.
Among those gems was Trevenant, a rare aristocratic Elder Tree Pokémon, with the power to see into the future. Assigned to him were a Froakie, Frogadier and Greninja. Common soldiers, with a mission to protect him.
Frogadier turned to Froakie. "Hey! Can't wait for those rebels to get here!"
"Haha, yeah! When I see those rebels, I'm gonna throw frubbles right in their faces!" He responded.
"What're you saying? I'm gonna throw frubbles all over their bodies, and then it'll be over,"
"What if… I just frubble you!"
Froakie jokingly threw a frubble cloud at Frogadier, who caught it in his hand. Froakie stuck his tongue out.
Greninja cuts in. "Oh, come on. We'll frubble them together when we fuse. That's why they sent, uh, three of us?" He said, holding his three fingers up.
"Three this!" Frogadier threw the frubble at Greninja, who caught it and threw it back. Froakie got another clump and threw it back at Greninja. Froakie and Frogadier repeatedly threw frubbles at Greninja, who caught all of them. He soon threw them al back at once at lightning speed. The two jumped out of the way, and the piece was heading straight for Trevenant. Luckily, he brought his hand up, creating a barrier made of roots. It went back through the floor covered in frubbles.
"OH! I, um, I'm so sorry, I, let me, uh…" Greninja went to Trevenant, fumbling over words as well as his own hands.
"It's okay," He said. "It was bound to happen,"
"I, uh… Okay," Greninja said, confused but glad he wasn't in trouble.
"I, uh, let me," Frogadier joked under his breath, earning a shut-up look from Greninja.
"Now please wait here. I must attend to my duties," Trevenant said.
"Right," "Mmm," "Yes," the three responded.
Trevenant walked into Articuno's palanquin, where Articuno themself was perched on their pedestal. A shiny Kirlia stood next to them. Trevenant had been called to Earth by Articuno, specifically to share his vision of the future.
"Master Articuno, I have arrived," Trevenant said with a bow.
Articuno spoke. "Trevenant, tell me what will happen here,"
"I foresee the rebels attacking the mountain. Before they are cornered, they will defeat seven Pokémon, including my Froakie and Frogadier guards and myself. Immediately after my form is destroyed, the rebels will be captured. The rebellion ends here," Trevenant exclaimed.
"Thank you, Trevenant," Articuno said, relieved. "That's all I needed to know,"
"I look forward to speaking to you again once I'm healed back on Homeworld," He said with a bow, before walking back to his guards.
Trevenant knew he would be a casualty, but it didn't faze him. He saw his whole life laid out before him, and he'd already accepted all of it.
Trevenant turned to Greninja, the closest to him. "What a beautiful place to inhabit. I wish I could've seen more of this planet,"
Greninja looked over. "Uh… There's still time," He said with a shrug.
"That's a nice thought, but… No,"
Suddenly, the ground rumbled as if there was an earthquake. Many Pokémon started yelling.
"Articuno, leave this planet! This habitat will not be completed!" A mysterious voice said.
"It's the rebels!"
"Who are you?!"
"Show yourselves!"
Suddenly, two Pokémon appeared. One of them was shining brightly, rose-colored gemstones coming out of their rocky body. Diancie. With her stood her second-in-command, a Kirlia.
"We… Are the Crystal Gems!" They said together.
Articuno's palanquin closes, sealing them inside. Shards of ice grew out from the bottom, which moved in a fashion to get the platform away from the attack, right on schedule.
The Kirlia's eyes glowed as she used Confusion on two gems coming towards her, and then doing the same to the other two going after her.
Froakie, Frogadier and Greninja all let out battle cries, jumping together before becoming one larger Greninja, with light frubbles coating its tongue/scarf. They summoned a water suriken and threw it at Diancie, who summoned a storm of diamonds. They all cut through the suriken and then hit the three. They unfused, and with two more attacks, Froakie and Frogadier fainted. Greninja fell to the ground and watched the Kirlia, eyes still glowing, stand in front of Trevenant.
Greninja suddenly realized what Trevenant had meant. He'd known that Greninja would fail, he had accepted it. But Greninja… Greninja could not.
"NO!"
Everyone looked to Greninja, who pounced to Trevenant. He pushed him out of the way, sending them spinning to the side. A bright light enveloped them as their bodies merged into one.
"Wha…" The new fusion looked down at himself, wondering what had happened. Their eyes widened. "What...?!"
Other Pokémon watched, horrified, at the completely different Pokémon standing there.
"What… What is this?"
The new Pokémon standing in place of Greninja and Trevenant looked… Strange. He had tree branches going up his head like ears, then had a mixture of leaves and clouds in between them. He had two eyes that belonged to Greninja, and one that belonged to Trevenant. They had no neck, just… Darkness. Their body looked like one of a Greninja but then had bark growing on one of the sides. One arm looked like Trevenant's would and the other like Greninja's, which was the same for the legs/roots. A vine was draped around their shoulders like a scarf. This Pokémon was a fusion.
The Kirlia watched, shocked, but shook it off. She readied herself to pounce again, but Diancie stopped her.
"Wait! This is… Hm?" She realized she attracted attention to herself and Kirlia. "… Let's go,"
Kirlia looked to her, confused. "Uh… Bye!" She and Diancie jumped away.
"Is this..?"
Greninja and Trevenant unfused. The crowd closed in around the two. They'd never seen a fusion between two different species of Pokémon.
"Unbelievable!"
"Disgusting!"
"This is unheard of!"
Articuno approached. "The rebels have fled. Trevenant, this was not the scenario you described!"
Trevenant was confused. "This is… Not what I saw! I don't know what happened, I…"
"NO!" Everyone looked over. "It was me!" Greninja exclaimed.
"Clearly," Articuno said.
"How dare you fuse with a member of my court?" They exclaimed, angry.
"Forgive me! I..!"
"You will be killed for this!" They said, closing their claw.
The crowd of Pokémon began to close in on them, but Trevenant grabs Greninja's hand and dashes off with him.
"Wait! What are you doing?! Nooo!" Greninja yelled. Trevenant jumped off the edge of the mountain, falling through the clouds. They eventually reach the ground, many roots catching them to soften their fall.
Greninja looked angered. "UGH! Why'd you do that?! I have to get you back up there!"
Trevenant trembled. "They were going to break you!"
"Who cares?! There's tons of me!"
He looked up into the snow that was falling from above, then at the surrounding area, then back at Trevenant. He groaned. "What do we do now?!"
Trevenant had known every moment of his life. How it would happen, and when. But because of Greninja's impulsive gesture, he suddenly jumped the track of fate, and everything from that instant on was wrong, he couldn't see, he couldn't move. He was… grounded.
Trevenant's roots had absent-mindedly grown into the ground. Greninja groaned. "Ah! We have to get you…"
He pulled Trevenant out of the ground. "… Out of here!"
Greninja held Trevenant, despite his size, in his arms. "Come on,"
Greninja walked away from where they'd fallen, Trevenant growing small leaves and buds on his body. Before either of them knew it, Greninja found a cave. He set Trevenant down once they were inside.
Trevenant looked up at Greninja, looking at him with one eye. "Thank you…"
Greninja looked at him, speechless. A drop of water fell from Greninja's hand. He looked down at it, then back at Trevenant, blushing.
Later, the two sat at the far end of the cave. Greninja had a small pool of water that Trevenant had some of his roots in. "Thank you… Again," He said, chuckling.
"No problem," Greninja answered, scratching the back of his head.
"What kind of Greninja am I supposed to be? Look at this! It's my fault you're stranded here. How am I gonna save you?" He said, talking to himself.
"You already did," Trevenant answered. Greninja looked up.
"What?"
"You already saved me,"
The two sit in silence for a moment, thinking about the strange day they'd had. Suddenly, Trevenant spoke up.
"I… I've seen Pokémon fuse before, but I had no idea that's what it felt like. I always thought… I never realized fusion… That you'd disappear like that,"
Greninja looked up. "It's never like that! Whenever I've fused, it's always just been me, but bigger, I… I've never had a third eye before,"
"I'd forgotten ever having more than one! It was nice," Trevenant responded.
Greninja blushed a bit. "Haha… Yeah…"
The two step out of the cave. The sun came up and it's no longer raining. They explore the Earth together, finding many strange creatures. Trevenant held up a frog to Greninja, who responded by lifting a tree out of the ground. They both laughed together.
They had fun that day. That night, they'd looked up and stared at the sky covered in stars.
"Oh… Um…" Greninja started to say.
"Well, I guess I've been thinking,"
Trevenant looked over. "So… Um… Did you say I was different?"
"And you hadn't before?"
"Oh course not! When would I have ever?"
"I'm so sorry…"
"No, non don't be!"
"And now you're here forever!"
"What about you?"
"What about me?"
"Well you're here, too. We're here together,"
The two Pokémon get up. They each reach out for each other. They dance under the moonlight, humming a soft melody together. Soon, they were enveloped in light. They were fused into one and their new form appeared.
He, whoever he was, was back. He was someone and he didn't know who. He felt like he was getting the hang of their new form. And then they fell.
"Ouch…" They said, rubbing their head.
Suddenly, a glowing hand was pointed towards his face. They shot back, surprised. "AH! Don't hurt him! Don't hurt… Me?"
A Kirlia, the Kirlia, kept their hand pointed at their face. "It's you! The fusion…"
They panicked. "We didn't mean to fuse! Well, we did this time. We'll unfuse! We'll…"
"No no, please… I'm glad to see you again,"
Diancie appeared behind Kirlia, then next to her. There they were: Diancie, the leader of the rebellion, and her terrifying renegade Kirlia.
"I don't upset you?" He asked.
Diancie chuckled. "Who cares about how I feel? How you feel is bound to be much more interesting,"
They looked at her, confused. "How I feel? I feel… Lost… And scared… And… Happy. W-why am I so sure that I'd rather be this than everything I was supposed to be, and that I'd rather do this than anything I was supposed to do?"
Diancie laughed. "Welcome to Earth!"
"C-can you tell me? How was Greninja able to alter fate? Or, why was Trevenant willing to give up everything? W-what am I?!"
Diancie shushed them. "No more questions. Don't ever question this," She reached out and held their hands. "You already are the answer,"
Love.