Based on my Snivy OC. Enjoy!

Caitlin walked around the woods.

She wasn't on any particular mission, just taking a stroll. She was supposed to be at the Pokémon League in Unova, waiting for a challenger. But she was the easiest to defeat out of the Elite Four, and besides, no challengers were gonna arrive for at least another two weeks.

"Taking a stroll, doo doo doo doo….Oh, what's this?"

A Snivy was leaning on a tree, typing something on his…tablet?

"If I don't do anything soon, we might not…" he mumbled quietly. Then he looked up and saw Caitlin.

Yes, I know Pokemon can't actually talk, but at this moment I don't even care anymore. You HAVE seen fanfiction of Pokémon talking, haven't you?

"Oh, hello there, ma'am." The Snivy said. Caitlin could sense an uncomfortable dark aura coming from Snivy, but she ignored it.

"You seem lonely. Do you mind if I…." Caitlin said while taking out a Poke Ball.

"I have nothing else to do anyway. Very well! It shall be as you wish." Snivy said. He was sucked into the Poke Ball, unwilling to break out.

Three months later….

Caitlin's last Pokémon was fainted.

"Woo-hoo, we did it, Haxorus!" Hilbert exclaimed as he high-fived his Haxorus.

Snivy was standing behind Caitlin, watching the battle.

"Very impressive." Caitlin calmly said. "You did very well in not giving me a battle where I could've fallen asleep."

"I'm the first of the Elite Four you've defeated, right?Keep going th-"

"Um, Ms? Can I battle your Snivy?" Hilbert asked.

Caitlin thought for a moment. "Very well. But this battle won't count. I'll even heal your Pokemon after."

Snivy walked into the battlefield, a little nervous.

"Alright, Haxorus, let's try to get another win here!" Hilbert shouted.

Snivy suddenly felt a tingling feeling in his body. This feeling….could it be?The same feeling I had at least a few years ago?Is it about to happen again…?

…dark…

Haxorus suddenly used Dragon Pulse, knocking Snivy back half a meter.

…aura…

The two trainers suddenly felt an uncomfortable breeze.

"Wh-what's going on…?" Caitlin said.

"This feels strange…." Hilbert mumbled.

Then suddenly….

A dark explosion suddenly emerged from Snivy. When the smoke cleared, he looked…..different?

The green parts of his body had turned black. The curved, yellow structures from his shoulder had turned red. His eyes were an even deeper red, with no pupils at all.

"Woah!"Caitlin and Hilbert both exclaimed.

Without a command, Snivy summoned a black blade with a red handle and slashed Haxorus. Haxorus fainted instantly.

"Eek! I think that's enough battling…"Hilbert exclaimed.

Caitlin healed the Haxorus, still in shock of what happened. Hilbert stood still for a bit, then walked to the portal and disappeared.

A day later…

"You sure you're fine without a trainer?"

"I'll be fine, Caitlin." Snivy said. He was back to normal.

Caitlin sighed. "Well, that dark form of yours…..I guess you can handle yourself. Farewell, I suppose."

Snivy nodded, then ran away. In a matter of seconds, he was out of sight.

….!

A portal appeared in front of Snivy.

Spoiler alert:This is gonna be one of the prequels for a future fanfic called The Apocalyptic Trilogy, a sequel that takes place 4 years after Dimensions Collide. But that's not coming for a LOOOOOOOOOOOOOOOOOONG time.