A/N

So this obviously takes place some time pretty early in Firhaur's revival, as this is the first time he's witnessed Gaster's temper towards his less cooperative projects.

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The Royal Scientist was getting rather frustrated.

Well, one of them, at any rate. Gaster was getting beyond annoyed with his current project- or, rather, the failure of said project. Firhaur, on the other hand, remained calm as usual.

He was, though, a little shocked to see the method of stress relief Gaster had seemingly developed in his absence. He was also mildly concerned with the damage expenses the lab must have been charging. Mugs, pens, chairs, and other such commodities weren't particularly expensive, but the costs racked up! Especially when this was apparently a common occurrence!

So Firhaur came up behind Gaster and wrapped him in a tight hug, pinning his arms to his sides, just in time to prevent the smaller of the two Royal Scientists from putting yet another dent into the side of a filing cabinet. "Brother! Calm down! Surely, there are less... destructive methods to vent your anger!"

Gaster struggled in the dragon's grip. "Firhaur-! Let- go!"

"No." Firhaur replied stubbornly, sticking his nose in the air, partially to avoid being head butted in the face, partially out of snarkiness. "Not until you calm down."

Gaster let out a sort of grrrrRRAAAAHHH noise and attempted to break out of Firhaur's arms, but Firhaur just squeezed him tighter.

"I said, no."

After a few minutes, Gaster let out an annoyed hhrmph and crossed his arms as best he could. "Fine. There. I'm calm now. Happy?"

"As long as you're not going around breaking lab equipment, yes, in fact, I am." Firhaur released Gaster.

For a long second, Gaster just looked at Firhaur, a funny look in his eyes that Firhaur thought he maybe should have been slightly concerned by. But then Gaster turned away without a fuss, back to his project. Firhaur gave a nod of approval, and turned back to his own work.

Less than a minute had elapsed, though, before Firhaur found himself not in the lab, but in a grassy field, evidently having been teleported by Gaster- and before the dragon could really even fully take in this information, he heard his brother letting out a savage scream to his left.

Turning with feline reflexes, Firhaur was just in time to avoid getting whacked by the bone in Gaster's hands. It was non-damaging, Firhaur had no doubt, as Gaster would never do anything to harm him, but it was still something of a shock.

"Now just what do you think you're doing?" The dragon huffed, sinking into a defensive position as he moved warily around his brother.

Gaster stayed crouched and ready, gripping the bone with both hands like a sword. "You said as long as I wasn't breaking lab equipment." He responded shortly through gritted teeth.

Firhaur smiled, just a little, showing off a number of his sharp teeth. "Well. If that's the way you want to relieve stress-" here, he lunged forward, around Gaster, and whacked Gaster with the fan of his tail in passing, sending his brother sprawling- "then I suppose I'm game."

As Firhaur began to circle him again, Gaster climbed to his feet, his snarl shifting to something that was almost a grin. "Good!"

And with that, the battle was on.

Having been in a healing hibernation throughout most of the war, Firhaur had not been around for the invention of Gaster's weapons. He had not seen Gaster in action, not with bones nor the Blasters made in his own likeness, and as such, knew not what to expect. He did, however, possess incredibly fast reflexes, his own natural Magic in the form of purple fire he could breathe out at will, and the power of flight that Gaster didn't immediately possess.

Using these skills, he agilely leaped forward, just barely dodging the multitude of bones that speared up from the ground. When he reached Gaster, he opened his mouth, bathing the skeleton in purple flames- non damaging, of course- before launching himself skyward to avoid retaliation. With just a few quick flaps of his wings, he was high among the clouds, looping, and then plummeting back down in a steep dive.

As he approached the ground, his sharp eyes picked out Gaster, running across the field, coat flapping behind him, in an attempt to avoid the dive bomb attack. Firhaur just grinned and tucked his wings in tighter, speeding his descent, only for Gaster to dive and roll to the side just in time. Firhaur started to pull up, intent on rising skyward again to make another pass, but he suddenly felt a strange weight in his chest, and he slammed into the ground, skidding some distance, leaving a huge rut in the ground.

Picking himself up from the ground, Firhaur saw the blue aura glowing against his chest. Blue Magic- he was effectively grounded. Then he looked to Gaster.

Standing some thirty feet away, the tall skeleton had a ferocious grin him his face. Oh, he was having fun! Sure, he was limiting himself to the use of Magic only, no Void attacks, but Firhaur was proving to be a more than capable sparring partner.

Lifting one hand, Gaster snapped his fingers, summoning two draconian skulls, eyesockets bleeding with purple light. Firhaur's lips drew back in a challenging snarl, and he leaped forward. In seconds, he had reached a full sprint, and as the Blasters loosed their deadly beams- or not so deadly, as it was still all non damaging Magic- the dragon lunged upward, wings spread to achieve more lift against the Blue Magic. Just in time, he jumped high enough to avoid being caught in the Blasters' crossfire.

And then, wings still spread, he sailed right over the beams, and suddenly dropped straight down to pounce on Gaster, and, startled by the sudden assault and knocked to the ground, Gaster released the Blue Magic on Firhaur's Soul.

Finding he could once again fly, Firhaur wasted no time in propelling himself upward. Now, though, he found the sky filled with the hot beams of Blaster fire. He twisted and rolled and ducked and dived in the air, but even his skill was no match for the chaotic maze of lasers that shot through the air. One wing was clipped by a beam, leaving a warm, tingling feeling, and his tail took a direct hit.

Seeing only more Blasters appearing around him, Firhaur decided it would be best to once again return to the ground, so he angled downward and folded his wings once more for a steep dive.

This time, he slammed into the ground some distance away from Gaster, and immediately let loose with a stream of fire, blasted in Gaster's direction. Gaster just managed to get up a wall of bones before the assault hit him, but as Firhaur slowly made his way forward, keeping up a continuous jet of purple flame, the wall began to break down. Gaster took a step back and hastily constructed another wall, but now Firhaur was only a few feet away, and this one started to break down quickly as well under the constant barrage of Magic.

And then, suddenly, the fire stopped, and before Gaster could respond, Firhaur was leaping over his wall of bones, landing squarely on top of Gaster, pinning him to the ground.

The dragon grinned down at the skeleton. "Had enough yet?"

"Fine," Gaster huffed. "You win. But only because you're my brother and I'm letting you win!"

"Suuuure," Firhaur replied skeptically, stepping back, then offering Gaster a hand in getting up.

For a moment, the two just stood in the field, looking around. There were massive scorched areas in the grass, and there was also that huge rut in the ground where Gaster had slammed Firhaur down with Blue Magic.

The two brothers looked at each other.

"Sure did a lot of damage," Firhaur said.

"Wasn't lab equipment, though," Gaster replied, shrugging.

"True." Firhaur nodded a little.

"We should probably get out of here," Gaster suggested, laughing.

"Also probably true."

With that, Gaster teleported then back to the lab.

The next day, a few kids would find the scarred battlefield, and begin the rumors that aliens had crashed near Ebott town, repaired their ship, and left in the night.

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A/N

Just a quick little friendly battle between siblings! Looks like Firhaur won... this time!

Anyway, thanks for reading, and I hope you enjoyed it! Comments and votes are my Favorite Things and biggest motivators, and every notification I get makes my day!