Fairy Tail:Celestial Tempest

Four years had passed, a blur of intense training and unwavering determination. Lucy was now thirteen, a formidable warrior with a lean, powerful physique. Rimuru had poured all his knowledge into her, teaching her swordsmanship, martial arts, magic, and even the forbidden arts of black flames, black lightning, and void magic. These three were a struggle, but Lucy, with her iron will, eventually mastered them all.

"Alright, Lucy! Show me that void strike again!" Rimuru yelled, dodging a blast of dark energy. "Remember, control is key!"

Lucy nodded, her eyes glowing with dark power. She focused, and a sphere of pure void energy materialized in her hand. With a sharp cry, she hurled it at a nearby boulder, obliterating it into dust.

"Perfect!" Rimuru exclaimed, clapping his hands. "You've mastered it! All of it!"

Seriously, this kid is a monster, he thought, his eyes wide. Black flames, black lightning, void magic… she's mastered everything I've thrown at her! And she's only thirteen! Did I create a monster?!

Despite her incredible power, Lucy's mind remained focused on one thing: revenge.

"Sensei," Lucy said, her voice cold and determined, "I won't forget my promise."

"I know you won't, Lucy," Rimuru sighed, knowing he couldn't change her mind.

Suddenly, Lucy flexed her arm, her biceps bulging. "Hey, Sensei! Look!" she said, a rare grin spreading across her face. "I've got bigger biceps than you!" She burst into laughter.

Rimuru blinked, then stared at her arm. "Wait… how the actual…?! You're right!" he exclaimed, dumbfounded. "How is that even possible?! You're just thirteen!"

Did I accidentally create a super-human? he thought, his mind reeling. This is getting out of hand!

In the middle of their training, as Lucy was effortlessly shattering a metal Rimuru had forged with his strongest materials, a sudden noise interrupted them. A thirteen-year-old boy with pink hair and a blue cat landed in the clearing.

"Whoa! What was that?!" the boy exclaimed, his eyes wide.

Lucy turned, her eyes widening slightly. He's… cute, she thought, a blush creeping onto her cheeks. How can someone look so innocent?

Rimuru, noticing Lucy's reaction, raised an eyebrow. Oh, this is new, he thought, a mischievous grin spreading across his face. Lucy's blushing! This could be it! A Fairy Tail fan's dream come true! Set sail, my ship!

"Hey! Do you guys know where my father is?" the pink-haired boy asked, his voice filled with urgency. "I heard there's a dragon around here!"

"A dragon?" Lucy asked, her blush fading.

"Yeah! Igneel! He disappeared on July 7th, year 777X!" the boy said, his voice filled with worry. "And today's the same day! I think he might be here!"

"Wait a minute…" Rimuru muttered, his eyes narrowing. "July 7th, 777X? That's… that's way off timeline! And this location is way further than Magnolia!"

He glanced at Lucy, who was now engaged in conversation with the boy. Wait, she's talking to him?

"I know how it feels to lose someone," Lucy said softly, her eyes filled with understanding. "Family… it's important."

"Yeah…" the boy said, his voice filled with sadness.

"I'm Lucy Heartfilia," Lucy said, extending her hand. "What's your name?"

"I'm Natsu Dragneel!" the boy said, shaking her hand with a wide grin.

Rimuru watched, his mind racing. This is… this is a major deviation! Lucy and Natsu meeting like this? This could change everything! He thought. And Lucy's actually making friends!

"Ah… since my dad's not here…" Natsu said, his voice cracking, his eyes brimming with tears. "Can… can I stay here for a while? Just… watch you train?"

Lucy's heart ached. He looks so sad… and he's even cuter when he cries, she thought, her cheeks flushing slightly. Focus, Lucy, focus!

She nodded, her expression softening. "Sure, Natsu. You can stay."

Lucy turned back to the metal Rimuru had forged, her eyes hardening. She raised her fist, and with a powerful punch, she dented the impossibly strong metal. Thump! Another punch, another dent. Thump! Thump! Each blow left a visible mark, a testament to her raw power.

Natsu stared at her, his eyes wide with awe. "Whoa… she's amazing!"

Rimuru smirked, nudging Natsu with his elbow. "She's beautiful, right? Don't you think, Natsu?"

"Yeah… she's beautiful," Natsu mumbled, his eyes still glued to Lucy.

"Come on, Natsu, do something!" Rimuru whispered, trying to push him into action.

"Yeah, she's beautiful…" Natsu repeated, his face turning red.

"Natsu has a crush!" Happy chirped, flying around Natsu's head.

"Shut up, Happy!" Natsu yelled, his face now a vibrant shade of crimson.

Intrigued, Natsu stepped forward, his eyes fixed on the metal. "Can… can I try?" he asked, his voice filled with a mix of curiosity and determination.

"Sure," Lucy said, stepping back. "But be careful. It's really strong."

Natsu nodded, his eyes blazing with his signature fiery determination. He raised his fist and punched the metal with all his might. "Fire Dragon's Iron Fist!" he yelled.

Clang! The sound echoed through the clearing, but the metal remained unscathed. Natsu winced, clutching his hand. "Ouch! That's hard!" he cried, tears welling up in his eyes.

Lucy stepped forward, her expression concerned. "Here, let me see," she said, gently taking his hand. "Why is your punch breaking that metal?" Natsu asked.

"Well… I've been training," Lucy said, a small, shy smile gracing her lips. "A lot."

Lucy stopped her training for the day, deciding to spend time with Natsu. "Hey, Natsu," she said, her eyes sparkling. "Let's play!"

"Play?" Natsu asked, tilting his head.

"Yeah! I've never really… had anyone to play with before," Lucy said, her voice soft. "You're my first ever friend."

Rimuru watched them, a genuine smile spreading across his face. It was the first time in eight years he'd seen Lucy smile so genuinely, so freely. She's finally making friends, he thought, his heart warming. Maybe, just maybe, she can find something more than just revenge.

Three days passed, a surprisingly peaceful interlude in their otherwise rigorous routine. Rimuru watched from a distance, a soft smile on his face, as Lucy and Natsu spent their days together. For the first time in eight years, Lucy had stopped her relentless training, choosing instead to laugh and play with her new friend.

"Come on, Natsu! You can't catch me!" Lucy giggled, darting through the trees, her laughter echoing through the forest.

Natsu, his face flushed and his eyes sparkling, chased after her, a wide grin plastered across his face. "I'm gonna get you, Lucy!" he yelled, his voice filled with playful determination.

Rimuru watched them, a warm feeling spreading through him. She's… she's actually enjoying herself, he thought, his heart swelling with a strange mix of pride and relief. This is good. This is really good.

He remembered the Lucy he'd first met, the child consumed by grief and driven by revenge. Now, he saw a glimpse of the girl she could have been, a girl filled with laughter and joy.

As they played, Natsu spotted a vibrant wildflower, its petals a brilliant shade of crimson. He plucked it from the ground and, with a shy smile, approached Lucy.

"Here," he said, holding out the flower. "It's pretty, like you."

Lucy blushed, her eyes widening slightly. She gently took the flower and, with a hesitant smile, tucked it behind her ear.

"Thank you, Natsu," she said, her voice soft.

Natsu grinned, his face turning a shade of pink that rivaled the flower. "You look good with it," he mumbled, scratching the back of his neck.

"Ahh, young love," Rimuru chuckled, watching the scene unfold, a mischievous glint in his eyes. "They're so cute!" He leaned back against a tree, a soft smile playing on his lips. "This is way better than watching celestial bodies collide, that's for sure."

The peaceful scene was suddenly interrupted by Natsu, who stood up, his face filled with a mix of sadness and determination.

"Ah… Lucy," Natsu began, his voice slightly shaky. "I… I gotta go."

Lucy's smile faltered, her eyes widening. "Go? Where?"

"Back home," Natsu said, scratching the back of his neck. "The guild… they're probably worried about me. I've been gone for two weeks."

"Two weeks?" Lucy gasped, her eyes filled with concern. "That's a long time!"

"Yeah," Natsu said, his voice filled with a hint of guilt. "But… I had a lot of fun with you, Lucy. You're my best friend."

Lucy's cheeks flushed, a small smile gracing her lips. "You're my best friend too, Natsu."

"I'll… I'll visit you sometimes, okay?" Natsu said, his eyes filled with sincerity. "I promise!"

"You promise?" Lucy asked, her voice filled with a hint of doubt.

"Yeah! I promise!" Natsu said, his voice firm. "I'll come back as soon as I can!"

"Okay," Lucy said, her eyes softening. "I'll be waiting."

Natsu grinned, his signature fiery determination returning. "Alright! See ya, Lucy!" He waved, then turned and ran off into the forest, Happy flying close behind.

"Bye, Natsu!" Lucy called after him, her voice filled with a mix of sadness and hope.

Rimuru watched them, a thoughtful expression on his face. Well, that was… bittersweet, he thought. But it was good while it lasted. Lucy actually had fun, and that's what matters.

He approached Lucy, placing a hand on her shoulder. "He'll be back, Lucy," he said, his voice reassuring. "He promised."

Lucy nodded, her eyes still fixed on the direction Natsu had gone. "I know," she said, her voice soft. "But… it's still sad."

"It's okay to be sad," Rimuru said gently. "But don't let it consume you. Remember, you have a purpose."

Lucy's eyes hardened, her expression turning serious. "I won't forget, Sensei," she said, her voice filled with unwavering determination. "I'll never forget."

Rimuru sighed, knowing he couldn't change her mind. "Alright, Lucy," he said, his voice firm. "Let's get back to training. We have a lot to cover."

Lucy nodded, her eyes filled with a renewed sense of purpose. "Yes, Sensei."

He'll be back, Rimuru thought, watching Lucy pick up her sword. And when he does, I hope she'll be ready. Ready for anything.