~~ ** ~~ THE INDESTRUCTIBLE DUO ~~**~~

"Effie, how many times do I have to tell you that you have to wait for my go-signal before you begin to attack?"

A frustrated rant echoed throughout the forest. In the middle of a battered clearing, a young mage, aged 18, stood with his fists tightly clenched. Under the blazing heat of the sun, the streaks of royal blue glistened from his hair of obsidian colour. He scratched his head in annoyance, looking fiercely at the coral-haired maiden in front of her.

The said maiden stood with a stoic expression, studying her nails. She let her companion continue berating her even though he was slowly getting on her nerves.

"Useless key holder with a brain made of tiny flames," the dark-haired boy, Steel Fullbuster, uttered loudly.

"What did you say?" the maiden finally snapped.

Steel clamped his mouth shut. He knew she reached her limit. Effie Dragneel's patience had evaporated.

"Excuse me, water cooler, but you were taking your sweet time to attack that monster," Effie reasoned, the tips of her hair slowly turning into fiery red flames.

Steel took a step back. He could tell that fury was slowly building up inside Effie. The Celestial Flame mage's aura would always emit strong flames, starting from her hair, whenever she gets angry. He knew she was pissed.

"It's called a strategy. If you don't know the word, look it up," he muttered under his breath.

It was true. It wasn't because he couldn't decide what to do with the enemy. Steel was just trying to devise the best way to complete this mission. His mind was building a plan of the best way to counter the monster's massive and strong assaults.

Would it be better to freeze its body or enveloped him in a suffocating amount of water? As he was trying his hardest to ensure the quickest way to succeed, Effie ran towards the squid-like monster and emitted her strongest fire. Within seconds, it was engulfed in a red blaze and the odour of burnt flesh filled Steel's senses. As Effie finished it off, piles and piles of gunk exploded.

Thanks to Steel's quick reflex, he was able to release large amounts of water to stave off the flying goo.

This had always been the case whenever he goes on missions with Effie. The battles always started nicely, with the two complementing each other's fighting styles and magic. But by the middle of the battle, something would go wonky. It was either Effie not sticking to the plan, or Steel going all out.

They always ended up arguing and fighting.

Yet, they always ended up going together. After all, in their guild, Steel and Effie are known as the "Indestructible Duo".

Steel with his ice-water magic.

Effie with her Celestial Flame ability.

Individually, the two are the strongest. Together, they are undefeated.

Still, the argument did not cease.

"Just so you know, these 'strategies' of yours," Effie raised her hands to create air quotations. "They rarely worked."

"Rarely worked? What do you call that time I saved your flat ass from that foul-smelling demon 'cause you passed out? Or, even that time when you couldn't even defeat a low-ranked Wind User with your flame?" Steel huffed in arrogance.

Effie crossed her arms, her head titled high. "Hmph, I saved your butt more times than you did mine."

"Oh really, tell me then."

It took some time for Effie to give an example. Yeah, when was the last time, other than today, where she actually saved Steel from grave danger?!

"Ah, remember that time where you couldn't do anything with that illusion mage? You were just standing frozen on the ground. Yeah, that was me who snapped you out of it!"

Steel laughed, shaking his head. "How many times do I have to tell you it was intentional? That mage was a babe, and she was providing me sexy illusions of herself."

"Excuses, excuses. That's all your good at!"

"Admit it, you were getting jealous when she got too sexy and close to me," a naughty grin played on Steel's face. "Tell me, Effie, how did you break the spell again?"

A deep red hue splashed all over Effie's face. Just thinking about the tactic she used made her hair burst in flames again. "I told you to forget about that, ice cube!"

The grin on Steel's face remained. He closed his eyes. "How can I forget about it when I can still remember the softness of your lips and the feel of your sk—," his teasing was cut off when Effie assaulted him with her fire.

Really, thank god for Steel's inborn reflex. Because of that, he was able to dodge and create an ice barrier around him.

"Ha! At least I did that to snap you out of those illusions. If I recall, you blushed so hard not even your water or ice can cool you down," Effie retorted, a ball of flame formed in her right palm ready to throw at the onyx-haired boy.

"That's just your imagination, bonfire," he said nonchalantly. Steel stepped forward inching closer to Effie. They grew up together, so they knew what makes each other tick. In fact, he knew just how to handle the fiery woman.

Perhaps because they both inherited their respective fathers' magic and abilities, they also acquired the urge to fight and argue over the pettiest things. However, unlike Gray and Natsu, Effie and Steel found a way to end a fight or an argument.

They had been doing this since they were 12 years old.

Steel managed to reach Effie in two big steps. "Hey wildfire, perhaps it's time to end this fight."

Effie smirked at him with challenging eyes. "Yeah? Well, who's going to initiate it, icicle-boy?"

Steel leaned down. Effie tiptoed. Their faces met halfway, and their lips gently pressed.

"I will."

They said in unison. With their lips parted, the plan to end the fight was a passionate lip lock. Eventually, they had to pull away from each other to catch their breaths.

Both of them acquired their respective mothers' passionate characteristic.

"You know, we should always quarrel every chance we get," Steel winked at her.

Effie nodded. "Yeah, I agree. I think we should have an action-packed altercation just so when we resolve it, it's equally intense."

Steel raised a brow. He was impressed with her boldness. He brought a finger to lift her chin up. With his other hand, he brushed away the few strands of hair sticking on her cheeks.

"I challenge you to a duel, Effie Dragneel."

"I accept, Steel Fullbuster."

And fight they did as soon as they got back to Steel's apartment in Fiore.

They didn't stop until their clothes were tattered and strewn all over the floor. They continued until both were panting and sweating like crazy. Their battle voices echoed throughout the room, reaching the highest climax.

No one lost the fight. Both were the victors.

"My dad's gonna kill you," Effie's muffled voice reverberated on Steel's chest. She nuzzled her face on his smooth skin.

"Ah, not unless my dad gets to your dad first," he responded, encircling his arms around the slender shoulders of the celestial goddess beside him.

He was ready for another fight.

A/N: It was fun to imagine how the offspring of Natsu and Gray would be like. I'm sure I'm not the first who thought it'd be nice if their kids would end up together, knowing full well the friendship and rivalry between the two mages. I had fun writing it, and I hope you readers find it fun as well.