It was slightly challenging to get Papyrus to agree to set up the duel, but eventually, he conceded. Frisk had impressed the skeleton with his skill in battle, and while he didn't think the human could beat Undyne, he thought they might impress the woman enough to not capture them.

Frisk didn't think that was likely, but Papyrus was still in denial about what capturing the human actually meant.

So, after Papyrus left to give his daily report to Undyne and set up the duel, Frisk was left to his own devices. He decided to do whatever possible to give him the advantage in the fight, which basically meant gathering anything that could be useful.

While waiting for his magic to recharge, the human walked around Snowden and gathered the most useful items. Using the money Toriel had given him, Frisk bought the Manly Bandana and some healing items from the shop. Doing last-minute magic practice probably wouldn't help, so he decided to return to the skeletons' home and meditate while waiting for Undyne's response.

Right now, Frisk was trying to improve his control over his Aura. Whether or not it was the same power from the show he used to watch, he was sure there was more to it than defense. It didn't seem likely, but if it could be improved to the point where he could manifest a semblance, that might-

The door to the house slammed open and in came Papyrus.

"U-Undyne has accepted your challenge!" The younger skeleton brother called out, it seemed like he had run all the way back from Waterfall. "She said the fight will take place tomorrow, at noon, but agrees to meet at the border between Snowden and Waterfall."

That was good news. Frisk had tried pushing the fight a bit later, but she had at least agreed on the location. By challenging her to a duel, he got to have some control over where they would fight. Undyne was too proud to insist they fight on her favored terrain, and her changing the time was probably just to fit in with her concept of a duel better.

Now, there were only final preparations left to get done.

During the night, Frisk once again snuck out of the house, though he wasn't carrying anything this time. Quickly, he retraced his steps through Waterfall and back to the glowing mushroom puzzle. Finally, he reached into the nearby tall grass and grabbed the ballet shoes.

The human needed every advantage possible, and the gravity kick these shoes allowed was helpful in the last fight.

Eventually, he made it back to the house and tried to sleep on the couch. Unfortunately, the tension of the upcoming duel made it difficult to truly rest. Frisk fell asleep late into the night, his mind reviewing strategies to use in the coming battle.

—

It was time.

Frisk had crawled off the couch late but fully rested after his late night. Now, he was once again getting ready to fight the strongest opponent he had ever faced. Flowey was more terrifying but obviously weaker. Sans was trickier, but Frisk couldn't say he actually fought the relatively passive skeleton.

Undyne was pure strength incarnate. The way she used her INTEGRITY magic to fluctuate the weight of her armor gave the guardswomen incredible speed, strength, and durability. She might not have used too many magic attacks during their previous fight, but each one was done with precision and great skill.

"When I said to get a better plan, I didn't mean for you to abandon any strategy at all." Frisk was only slightly surprised by the lazy skeleton's voice. "A duel's not the greatest strategy if you're still weaker than her," Sans stated in a relaxed tone.

Frisk stopped rummaging through his bag and looked back at Sans, sitting casually on the couch and, more specifically, one of the human's extra sweaters. It was just like a sleepover; they hadn't given him a blanket to sleep with, so he had to get his own.

Rolling his eyes, Frisk shooed the skeleton off the piece of clothing; he was in the middle of packing, after all.

"She might be stronger than me, but that doesn't mean I lose automatically. I've taken away her terrain advantage while still having more information on her abilities." He pointed out more to reassure himself than Sans. "But that doesn't mean I plan to win this fight with just violence," Frisk smirked at the now confused skeleton.

"Dare I ask what you're planning?"

Frisk shook his head. "Aren't you going to be watching with Papyrus?" The younger skeleton had insisted on being there. "I wouldn't want to spoil the surprise." Plus, it was kind of embarrassing to say out loud.

This story originates from Royal Road. Ensure the author gets the support they deserve by reading it there.

After leaving with a chuckle and wave, Sans went to go get Papyrus from his guard duty post. While he was doing that, Frisk got everything ready and started toward the battleground. He was psyching himself up the entire walk for what was to come.

Their battle would take place on the border of Snowden and Waterfall, where the snowy terrain transitioned into the rocky floors of the underground cave. There was the river Frisk had to be careful about. It ran along the left side of the path to Waterfall and would be fairly close to their duel. His best bet was to use his range to kite the fishlike monster away from the water. The plan was to draw her further into Snowden and use the trees as cover to disrupt her speed advantage.

By the time Frisk had thought it through, he could already see the battleground and his opponent. The skeleton brothers were standing together off to the side. Looking over the human thought, Papyrus looked excited but nervous, while Sans… Sans held a cardboard sign that said 'Go Undyne!' scrawled almost illegibly in blue marker.

"Glad to know we have an unbiased audience." Frisk deadpanned and finally turned to inspect his opponent.

Undyne was still wearing her dark gray full-body plate armor, which made her look massive. Even though Frisk had shrunk, he was sure she had to be over six and a half feet tall in that thing. The warrior stood with her arms crossed, though Frisk could see her shaking slightly.

Maybe the cold was getting to her like he had hoped.

Taking a deep breath, Frisk marched up to stand before the giant.

"HUMAN," Her voice echoed from underneath the helmet. "As you have challenged me to a duel, I will wait for you to state your conditions for this match."

Frisk looked up at the armored figure and tried to appear confident. "If I win this duel, I request safe passage through Waterfall and that you no longer hunt me while I inhabit the Underground."

The human stared into the armored slits that held his opponent's eyes. He couldn't afford to show any weakness, even when negotiating the duel.

"Very well, and if I win this duel," Undyne reached out, and glowing blue energy that almost looked like water flowed out from her gauntlet to form her signature spear. "I will take your soul to give it to King Asgore and free the Monsters." She pointed her spear at Frisk's heart. "Do you accept these conditions?"

Some commotion came from the sidelines as Papyrus heard what was actually at stake. Luckily, Sans seemed to be able to calm his brother down, because the commotion eventually stopped.

Frisk's left eye lit up with JUSTICE magic as he gathered the energy into his hand. Lightning exploded from his fist with a clap of thunder and formed his bow. "I accept." He took a deep breath one more time.

"Great!" Undyne reached up and, for some reason, threw off her helmet. At that moment, she was no longer quivering in the cold; she was roaring to fight. "Then let us have a fair battle." She raised her empty hand in front of her face and did something weird with her fingers.

The human was getting ready to fight but when he was about to make his move, Undyne stopped and frowned at him. "Are you going to do the Seal of Confrontation too?" She asked, seemingly confused by his actions.

For a few seconds, Frisk stood there, struck by the absurdity of the situation. But maybe he should have expected this; Papyrus did say that he watched Naruto. Also, Undyne always seemed to take anime way too literally. She did think Humans fought with giant mechs, after all.

"This is how humans start a duel, right?" she asked, almost sounding embarrassed by his inaction.

Well, this might work better for his plan. "It's not exactly common practice when one of them is trying to kill the other." It's not common practice at all, but Frisk didn't feel like getting into that right now. He vaguely remembered Naruto and Sasuke doing this at the final valley, so maybe he could see where Undyne got this specific instance. "But it does seem rather fitting." So Frisk raised his hand and clumsily mirrored her hand sign.

"Haha!" The warrior shook off her embarrassment easily and lowered the sign. With impressive grace, she jumped back and started flourishing her spear. "HUMAN! For the sake of every monster in the Underground, for their hopes and dreams, I will defeat you right here and now!"

This was it. The time had come to implement his plan to beat Undyne.

Frisk pushed JUSTICE into his Aura before mirroring her same jump backward. However, this time, he backflipped for added effect. Landing with a pulse of yellow energy, Frisk twirled his bow around before pointing at Undyne with his free hand.

"Undyne! Even if I am weaker than you, I vow to win this duel here and now!" Frisk tried to sound as determined as possible. "Not only for my friends but also for every monster in the Underground. I won't allow you to stop me from saving them all!" He finished, his right eye glowing purple.

Yes, his master plan was to be a better anime protagonist than her.

"So come at me, and let me show the power I've gained from believing in myself and others!" He called out and watched as Undyne's face twisted in confusion.

Specifically, he constructed this whole situation to make her out as the villain of this story. It might have been manipulative, but Frisk knew that a lot of her self-worth came from viewing herself as the hero of the story. It was what allowed an ordinarily good person like her to justify killing a kid and stealing their soul.

"SO COOL!" Papyrus called out from the sidelines. He seemed to have overcome his surprise at the situation and had picked a side. Well, at least the audience was split evenly now.

Frisk hoped to use the fundamental incompatibility of her view of herself versus what she was doing to convince her to ally with him. From the humans, admittedly slim knowledge of psychology, he thought the cognitive dissonance would force Undyne to reevaluate her desire to kill him.

It definitely wasn't a foolproof strategy because when you challenge someone's beliefs like that, they can also respond with-

"Are You Mocking Me!?!?!" Undyne screamed as her INTEGRITY magic almost exploded from her armor, covering it in a large dark blue aura.

Anger.

The shadows in the area seemed to lengthen, and Frisk's soul shone on his chest.

Yellow energy sparked, and Frisk dodged back toward Snowden before Undyne even finished her sentence. His preemptive leap was the only reason he wasn't flattened by the warrior's first blow, which cratered the ground where he had been standing.