Toby Fox owns Undertale and all associated character.


Rex looked up as the older Frisk parted ways with their friend. They relaxed, only to jump with a yelp as the door opened, already drawing their weapon. "Hold, it, Rex!" The reptile blinked to see Gerson looking down, and then gave a sheepish laugh. "Heh, and I thought the Froggits were jumpy."

"Sorry, Gerson," they murmured, slowly sheathing the blade with their magic.

"Hang on… what was that just now?" Undyne demanded, looking down over the elderly turtles shoulder. "That looked like… ghost magic?"

"Uh…" Rex slowly looked up, then stepped back and hunkered down a little.

"Ghost magic?" Gerson questioned, then shook his head. "Actually, we don't know much about Rex's magic. They hadn't been showing any signs they even had magic until last month. It's Pink magic, and we've never heard of that type before. We don't even know the attribute for it currently. Rex's the first with this type as far as Humans and Monsters are concerned."

Undyne frowned, leaning against the doorframe.

"Pink magic? I don't… Oh right, Alphys said something about that this morning… your magic is color coded right? And there's different abilities for different types?" She gave the child a sympathetic glance. "And you got stuck with pink of all things. Still, I guess it's not too bad if it lets you grab stuff, our Kid could use something like that." She grinned suddenly.

"Though It's awesome to see we have similar ideas on how doors should be opened!"

"Y-yo, I'm just glad I have magic," the reptile managed, straightening when they didn't feel a threat anymore, before tilting their head in confusion. "...and what way do you open doors?"

Gerson glared up at the fish woman. "You break it, you buy it, Urchin," he warned.

"Depends on how much of a hurry I'm in. Feet or head all the way!" Undyne crowed, pumping her fist in the air. "I mean, who bothers with doorknobs anyway?"

"Ahem," the turtle called up as he folded his arms, tapping a foot. "They were invented for a reason. Please leave everything intact."

Rex couldn't help a smile. "Was our Undyne like that?"

"Oh, do I have stories for you about that Urchin!" Gerson suddenly smirked. "I remember when she was seven and she thought she could-"

"Uhh- Anyway!" Undyne interrupted hastily. "That looked like a decent knife there, do you actually know how to use that thing?"

Rex nodded. "Gerson's been teaching me stuff. I usually have it in my mouth, but I've been learning to use it with my magic...not a whole lot yet."

The tortoise gave a sound of agreement. "Kid asked me to start training them some time back when they were attacked along with Frisk. They managed to hold their own, and I thought-the more the merrier when it comes to protecting the Neck Warmer, so, we started training. Sadly, haven't done much in the past month, so Rex hasn't been able to try anything with their magic yet."

"What, getting too old for this?" The fish-woman teased, a grin spreading across her face. "I can always give the punk some pointers if you need an extra nap, old man."

"Were you drained of magic, Urchin?" the turtle asked, but shook his head. "I'm not above letting the kid learn a few more things if I'm not fit to teach currently," he said. The reptile went wide-eyed as they realized what the two were suggesting.

Undyne's eye focused on Rex.

"Ya hear that, punk? You're not getting out of this one! Let's see what you've got!"

The young monster stared, dumbstruck, while Gerson snickered. "Come now, don't break on me," he said as his little Frisk ran over to him with a smile. "I'll keep an eye on them, you actually get some training in," the turtle winked. "According to the world, you're their sword and shield, better live up to it."

"Right!" Rex managed, shaking their head hard, before looking up again, their claws digging into the soft ground.

"Sword and shield, huh? Sounds like you're a bit more of a fighter than our Kid," the warrior noted, striding past the younger Frisk and into the yard. "Hey, Frisk, you're gonna want to move your ass out of the way, unless you want another close up of one of these!" As she spoke, a spear materialized in her hand.

The teen's eyes widened and he quickly scrambled to his feet from where he had been seated in the corridor. His gaze darted between the warrior and Rex.

"Hey… just make sure you don't kill them alright?"

"I've been training warriors since long before you were born, punk. I know how to watch people's limits. Now are you getting out of here, or are you gonna join in?"

"Good luck!" The elder Frisk called to Rex before darting away, heading in the direction of Hotlands.

Rex blinked, and then hopped back, drawing out their blade, the dagger hovering in front of them as they dipped their head down slightly, watching the fish warrior. It was one thing to be trained by their Undyne through Frisk...and then to train with her face to face. They weren't quite sure what to expect.

"So, going with the dagger, huh? If you want this to be up close and personal…"

Without any other warning, Undyne leapt forwards, her spear aiming for Rex's side.

Rex leapt away, landing a moment later, but without waiting a moment, they were on the move again, smiling a little. They knew one thing at least, and that was not to be a sitting duck while Undyne was able to throw things. They wished they had been in the Ruin's garden though, as at least that yard had a tree to use for cover. They looked at Undyne, quickly realizing that being on her left side would be to their advantage.

"Not so fast!" The warrior grinned, clenching her free hand into a fist. Instantly, Kid's body was covered in a green aura, freezing him in place. "You might want to consider upgrading from that toothpick," she called, getting within reach again and thrusting her weapon at the child. "Unlike Chara's knives, that thing doesn't have any reach!"

Rex's eyes widened, before they shut tight, as they tried to summon the magic shield they had before. They opened their eyes, just as it formed.

The spear shattered the barrier on impact, though the unexpected resistance slowed the attack and deflected it slightly so the point barely scraped Rex's side. The fish-warrior grunted, pulling the spear back and lashing out at Rex's legs with the pole end.

"Eyes on your opponent! You've got two of them, make them count!"

The child hit the ground, summoning another shield as they swiftly fought to get back on their feet, their dagger hovering as they looked for an opening. Rooted to one spot was not good, but until they could move again, they had to stay on the defensive. Their side complained, but they ignored it.

As soon as they were back on their feet, Undyne hurled her spear at him and charged forward, swinging a fist at his midriff, moving just quickly enough that she would be in striking distance right after the spear impacted.

This time, Rex had their blade ready to use, no longer caught off guard by Undyne's soul effect, though they tried to move as much as they could as they swung it in defense, their eyes narrowed in concentration. If the effect would wear off, they could get out of this already!

Gerson leaned against the house, arms folded as he watched the kid fight, taking note of what needed to get worked on, and what the kid had gotten better at.

Undyne's spear shattered the shield once again, though this time, it too dissipated on impact. Her eye gleamed, the grin never leaving her face as she sank her fist into the reptile's stomach.

Frisk made a sound of alarm, though Gerson stopped them from doing anything as Rex cried out, tumbling across the ground and against the wall, however, when they looked up, there seemed to be a fire lit in their eyes as their dagger swung into the air and they managed to get to their feet, breathing heavily, but keeping their gaze locked on the fish woman as they struggled with the soul lock. They just-needed to hold on-a few more moments!

Seeing the child's gaze, Undyne's grin widened, almost impossibly. Then she gestured with her other hand, the aura around Kid dissipating with the motion.

"That's what I like to see! Now come on, hit me like you mean it!"

Rex hopped back and wagged their tail a little, their dagger moving in a beckoning motion, almost like a playful taunt. So long as she didn't use that soul trap again, this might actually work.

"What're you waiting for?" Undyne called impatiently after a moment. "Don't wimp out on me now, this is just getting started!"

They swayed their body, as if in thought, before lunging forward in rapid speed, but just before they came into reach, they crouched, as if to jump, and everything seemed to distort around Undyne before she found herself a few feet away from where she had been. She blinked in confusion before something crashed down on her shoulders.

The child's weight was negligible, Undyne could lift a car if she really wanted to. That was not the problem however. Her spear faded out of existence and she shuddered, then fell to her knees, vomiting onto the ground in front of them.

Rex yelped in alarm, quickly getting off her. "Yo-Undyne!"

Seeing the issue, both the turtle and Frisk rushed forth, while the reptile stared in shock, caught off guard by what was happening.

The fish warrior's shoulders heaved one more time and she looked up, panting slightly.

"What are you… looking at?" She demanded, struggling to her feet. "I'm fine!" She glared at Kid. "When I say, "Hit me like you mean it," That means hit me! Not… whatever the hell that just was!"

"I was...going to but…" They hadn't been sure what had just happened, and was now a little nervous over it. They had intended to strike-but it seemed that move was still unpredictable in more ways than one. It was not their intention to land on top of her.

Undyne narrowed her eye at him for a moment, regaining her composure.

"You have a teleportation power, kinda like Sans." She said after a moment. "I'm not sure what you were trying to do with that, But if you have that kind of power, then you'd better remember this. If the old man hasn't beaten it into you already." She took a step forward, her face serious.

"Don't ever attack someone from behind. Take them by surprise, or prepare yourself for an attack, I don't care. But if you're going to hit someone, then they'd better be facing you when your blow lands. Otherwise, you're no better than a common thug. Got it?"

The reptile nodded very slowly, head lowered, but gaze up. "Sorry," they mumbled. "I wasn't trying to land on top of you.."

Undyne looked at him for a moment before grinning and slapping the reptile on the back.

"Well, with that taken care of, are you gonna hit me or what?"

Rex gave a grunt and then looked to Gerson, who smirked. "So long as you don't skydive onto her again-or use that move-I think we're good. When I'm better, you can try it on me instead." Frisk started to move forward, but Gerson grabbed them, yanking them onto his shoulders. "No interference, Neck Warmer, you're too good at breaking them."

Undyne took a couple steps back, turning her head to spit before re-summoning her spear and readying her stance.

"Alright, Rex. Let's do it properly this time, alright?"

They nodded. "Right." With that, they drew out their dagger again, staring at it for a moment, an idea coming to them as they swiftly looked up. "Ready," they assured, shifting their stance slightly.

"You don't like making the first move, do you? Fine then, have it your way!" She charged with a battle-cry, her spear extended straight towards Rex's midriff.

Rex waited for her to draw closer, before they jumped up, lashing out with their dagger, eyes narrowed, a bit more calculating now. I prefer to be a shield… they murmured to themselves. And shields don't make the first move! As they came down, they spun, their spiked tail whipping in the movement.

The tip of the reptile's dagger scored a thin line across her collar, but Undyne did not slow her charge. Though her spear had now passed under him, her body smashed into the much smaller one, even as the tail slammed into her side. There was more force behind the blow that she had been expecting, but still, it was unable to slow or even divert her headlong charge.

Rex gasped as they were sent flying, and instantly summoned another shield as they quickly regained their footing, though they found their new magic was making it much easier to find their balance. Their body complained about the sheer force slamming headlong into them, but the child was stubborn, and refused to go down that easily. Even so, they were starting to tire. Realistically speaking, they would want to find a way to end the fight soon.

"Defending isn't always an option kid!" Undyne called, spears forming in the air behind her and pointing at the young Monster. "If you're fighting someone stronger than you, you have to finish the fight as quick as you can. Besides," she added, flicking a wrist and letting the spears fly towards him. "Haven't you ever heard? The best defence… is a good offence!"

Rex darted to the side, jumping and spinning to evade the spears, before jumping against the wall, and using it to propel themselves forward, their blade lashing out as they drew near.

Undyne didn't attempt to block the hit, instead smacking the butt of her spear against the child's legs, just hard enough to ensure that he wouldn't be landing comfortably as she took the blow.

She grimaced.

"Come on, is that the best you can do?"

They crumpled to their knees, and then shakily jumped back to evade any possible counter attack, and then came forward again. They darted around Undyne's feet, hoping their quick footwork would help them trip her up. Still, this was Undyne...

Undyne frowned down at the child, unaffected by their attempt.

"Uhh… What are you doing?"

The reptile spun on a dime, tail whipping for her legs as the dagger swung high, eyes wide, but focused.

Undyne grunted with the impact, even as her spear lashed out, knocking the young Monster away. She put her hand over the wound, inspecting it for a moment, before grinning.

"Now that's a decent hit! Too bad it took till now for you to do it but, at least I know you got it in ya." She opened hand, her spear falling from it, fading away before it hit the ground. "You alright over there punk?"

The reptile's tail raised in a wave before they yanked their face off the ground, spitting out dirt with a disgusted look, not noticing the bit of red on their chin as they shakily got to their feet. "Fine…" they panted; sheathing their dagger.

The fish warrior strode over to the child.

"Decent work, for a rookie," she praised. "I hope in a real fight, you attack more often than that though. If you're gonna be using mostly physical attacks, then you're really gonna want a better weapon too.

"And remember, jumping around in combat is really cool, but you have to be careful with it. It can't be your first instinct. When you jump, you've committed yourself to a path, there's not much you can do to stop yourself. If we'd actually been fighting, I coulda skewered you when you jumped at me, and you wouldn't have been able to do a damn thing about it."

Rex nodded. "I tend to attack more often-this was just the first chance I got to try my magic attacks, so I wasn't doing stuff I'd normally do...and…" They dipped their head. "I'll be more careful with that."

Undyne reached down, rubbing the top of the child's head affectionately.

"Good. You'd better keep yourself alive, I want to see you get to the point where I can spar with you and take the kid gloves off." She stopped and groaned. "Do not tell Sans I said that."

"Yo-I know better," Rex managed, but looked up with a smile, their tail swaying out of barely contained joy. Frisk had to muffle a laugh. They'd burst later.

Undyne removed her hand and looked over to where the little Frisk sat atop Gerson's shoulders for a moment, grin widening.

"Well, what are you waiting for? You gonna go help your sword and shield celebrate or what?"

Frisk jerked their hood down to hide most of their face...but not their smile as they dropped down, adjusting the cloak before rushing over, hugging the reptile with a happy hum. "Frisk-!" They murmured something to the Monster, and turned them silent.

Gerson leaned back against the house, and shook his head with an amused smirk. "And they broke their sword and shield again...I need a better blacksmith apparently."

"Looks like those two are pretty close." Undyne smirked, folding her arms in front of her chest, "Not that I'm surprised, they'd have to be if Rex's got an awesome title like 'Frisk's Sword and Shield.'"

The old turtle chuckled quietly. "And the funny thing is that it was the humans that gave them that title. They've gotten pretty close over the years." His expression softened. "The kid's good at cheering them up, and while not fully up to the task physically, their heart's in the right place when it comes to Frisk's well being. Then again, had it not been for them coming along last month, we may not have made it through."

"Sounds like there's a story there," the warrior said. "You wanna tell it? It'd be good to know what he's was up to while ours was getting himself into trouble."

"Well, this one's a lot shorter than that other one." He slid down, and patted the spot next to him. "Come on, Urchin. Been awhile since I told you a story."