They couldn't understand her

Walls of bones emerged from the ground. With a move of a hand, the whole structure turned blue and aimed right at the human. Her soul turned blue as she jumped across the obstacle, one more centimeter and she would have lost most of her HP.

Papyrus adjusted his bullet pattern, now sharp bones appeared out of thin air and pierced right at Frisk, but she seemed to dodge all of them with ease. She rolled her eyes at the lack of challenge whilst dodging another bone aimed right at her, probably to annoy her opponent.

The skeleton took notice of the human's behavior and put on a satisfied grin. He already knew Frisk well enough to understand her. It didn't matter if she used her voice or not. A fight like this was a challenge he had waited to get for a long time. Ever since Undyne decided to go easy on him, fighting with her wasn't as fun as it used to be before. Papyrus shook his head and focused on the fight once again.

With a swift yet controlled motion he snatched his hand upwards. Frisk's soul moved up to the sky, slightly confused she tried to adjust herself to the gravity magic and dodge the attacks thrown at her, but she failed to notice a few of them. She lost 3 HP before Papyrus let go of her soul, returning its natural bright red color. Papyrus struck a pose and playfully winked at her.

Gasping for air, Frisk made her move. The snow clenched under her feet as she jumped upwards to punch Papyrus in his shining armor. With a sudden motion, he jumped back just far enough to avoid getting hit with her stick. he landed on the crunchy snow, with his cape flowing gracefully behind him. Frisk charged again, and this time the skeleton didn't even have to move to dodge the attack. Frisk stumbled on her feet before composing herself once again, she giggled at how silly this missed attack must have looked like, and Papyrus returned the giggle.

As the battle raged on, Frisk leaped over the sky-colored bone attacks whilst still being in the air. As another set of bones drew near she landed on the ground unevenly, making her lose balance. Luckily for her, all the attacks missed her. Papyrus turned his head around and again put his right hand in the air, summoning three bones right behind the human. There was no way The Great Papyrus would have ever lost to a human unless he wanted them to lose! The skeleton moved his arm faster, making the attacks faster and less in control.

This time, Frisk wasn't as lucky as before. Whilst two of the bones flew just conveniently enough for Frisk to dodge them, her lack of balance was still evident in her swayed movements. The third bone pierced forward, eventually hitting the unbalanced human right in the back of her head. She has lost 5HP, leaving her with only 12 of it left. Papyrus stepped backward at the sound of a bone attack hitting Frisk's skull.

Her eyes opened in surprise, pupils started dilating from left to right. The stick she held so tightly just a second ago dropped from her hand as she fell forward, landing with her face on the cold snow. Her eyes closed, and her lungs let out a deep breath before she finally passed out.

Papyrus put his hand down and immediately stopped attacking his now unconscious friend.
"Human! Hey, are you all right?" his skeletal frame hovered over her. She didn't answer his question, so without wasting time, he scooped her over into his hands. With little to no effort he stood back up and began running back to his and his brother's house. Panic pierced through him, but luckily, the human still had a bunch of HP left!

~~~~~~~~

The pet rock seemed almost satisfied, which was indicated by how silly he looked. Sans chuckled, then sprinkled a little bit more edible glitter on it, it was almost perfect. He told Papyrus he would feed it once he's gone, and he kept his word. The skeleton shifted his position in the chair and reached for even more glitter.

Just when he closed the tiny glitter box, the door swung open, and Papyrus emerged from it, still holding Frisk in his arms. "Sans! I don't know what happened!" he said with an apologetic tone "We were fighting, and then the human completely dropped to the ground! I'm so sorry!" Papyrus cried out to his brother with unleashed tears in his eye sockets. Sans' eye sockets lost their color for a moment. it only returned right after seeing the human's chest go up and down in a slow and repetitive motion. His brother probably didn't notice this.