Sans pulled his left hand up, and Percy was thrown high into the air, though he kept a firm hold on his sword. It felt like he was being yanked upwards by his soul like Sans was gripping it with his magic. The red heart had flown from Percy's chest every time he entered a Fight, but he had barely paid attention to it since his talk with Flowey.

He stopped moving midair and saw his soul turn from its usual red to a startling dark blue. Then he was thrown straight back down to the ground.

Before he crashed into the snow, Percy instinctively used his powers to pull up water from the river to give him a softer landing. He landed in the tentacle of water but was still being pulled down by his soul, so he had a rough landing.

Being constantly dragged downward made moving quickly more difficult, but there was no time to waste. Percy knew he had to up his game if he wanted to keep up with this monster, so that's just what he did.

Percy saw a red haze appear all over the ground where he was and instinctively jumped as high as he could. Just as he did, the area outlined in red was covered in bones stabbing up from the ground.

At the height of his jump, Percy saw a wave of bones flying at him. There was one curving, narrow space in the wall of bones that looked safe and he had to land in a roll to get there in time. Percy's soul changed back to red once he was on the ground, and he still had to quickly adjust his position to stay away from the bones.

There were more close calls than he could count, but thankfully, he managed to avoid all of the bones. None of the monsters he had met so far down here in the Underground had managed to do much more than scratch or bruise him, but he had a feeling he did not want to get hit by these bones if he could help it.

He could not be caught napping with this guy.

Just as those bones stopped coming, an array of giant animal skulls appeared, all eight of them facing toward him. The mouths of the skulls were all wide open, and they did not at all look friendly, so Percy ran out of their way, and was very glad he did when they blasted out what looked like might be pure magic energy.

Immediately after those skulls went away, a new group of them appeared in a different spot, and Percy had to quickly roll out of the way. When the third group of blasters appeared in the same spot as the first, Percy barely jumped out of the way in time.

Then when the last two blaster skulls appeared, bigger than the others and staring right into his face, Percy didn't quite get out of their range in time, and both his body and soul were blasted directly with magic.

Sans' attacks were even worse than the arai. When he killed those creatures they left with him the curses uttered against him by monsters in their dying breaths, and he nearly died to those creatures in the Underworld. But the way Sans' attacks worked against him was much more direct. While Percy was in the blast, he was immediately drained.

In the short amount of time he was stuck in that attack, Percy felt like he was being ripped apart, bit by bit. Memories of the hundreds of monsters he had killed flashed before his eyes. It felt like his sins were crawling on his back, dragging him down.

When the attack ended his HP had dropped from 252 down to 173, and even when the blast stopped, the pain didn't. His HP was still being drained, and Percy knew it was karma.

As Sans attacked with his magic, he stared at Percy with empty eyes. Everything had happened in less than ten seconds.

"huh." Sans shrugged, the white dots returning to his eyes. "always wondered why people never use their strongest attack first." The tense atmosphere burst, the silence shattering. It seemed like someone here was some kind of megalomaniac, but Percy honestly didn't know who. As Percy stared up at Sans in fear, he felt like he was going to have a bad time.

Get it together, he told himself. There's no going back, and I don't think Sans is planning on forgiving me anytime soon. I have to fight back. Percy gathered up his courage and swung Riptide at Sans. Not only that, but at the same time, he also used water from the river behind Sans as a whip, to give him the least chance of escape.

Sans ducked his swing and was forced to dive into a roll to dodge the whip of water on top of it. He jumped up and shrugged. "what? you think i'm just gonna stand there and take it?" But despite Sans' casual attitude, Percy could see he was shaken.

He wasn't the only one.

It was Sans' turn now, and he sent bones at Percy from both sides, and he had to do small jumps to get over them in time. He tripped on one of the last bones by accident, and through the haze of pain, he sliced his sword through the last two bones as they came, having no time to jump over them.

Percy was getting dangerously low on health. Then he remembered the pie! Percy pulled the slice of butterscotch-cinnamon pie out of his pocket, and, surprised by how good it still looked after being stuffed in his pocket for so long, quickly ate it all up. Just as he'd suspected, like ambrosia and nectar, it healed him back to full health, and considering the constant Karma, he was as ready as he would ever be.

Once Percy was done, Sans wasted no time talking and sent more bones flying at Percy. They came in groups of two: A tall blue bone too high to jump over, and a shorter white one just after. With no other way past the tall blue bones, Percy cut through them with his sword as they came. As soon as he sliced through the blue bone of a pair, the white one was on him, and he had to immediately jump over it.

In theory, he ducked, cut, and jumped, but in practice, Percy got hurt quite a lot by both colors of bones, and he gritted his teeth through the pain. At one point in the attack he could have sworn he didn't cut in time, but as Percy had crouched there the blue bone moved right through him. After that attack, his HP fell to 157, and it kept draining.

It was Percy's turn to attack now, and he again whipped water at Sans as he swung his sword, but this time he used three water whips instead of one. When he was attacked this time, Sans didn't even bother trying to jump away on his own feet, he just teleported behind Percy to get out of the danger zone.

Sans is tough, Percy thought. I haven't even been able to land a single blow yet. He's slippery. Next time I attack I'll need to be even more clever if I want to have a chance to land a hit.

Sans looked back at Percy and said, "our reports showed a massive anomaly in the timespace continuum. timelines jumping left and right, stopping and starting..." Like... time travel? But how could that be possible? Percy wondered to himself.

The next attack from Sans was similar to his first, with bones above and below coming from both sides. Unlike last time though, the bones' movement speeds were irregular, and he had to jump much higher to clear the bottom bone. This attack wasn't too bad, but Percy still got hit by one of the bones, lowering his health to 113/252, not accounting for the continuous Karma.

Percy flung his water whip out at Sans as soon as he could. Instead of also swinging with his sword, while Sans was distracted, Percy pulled out the little snowman from his pocket, brushed off the pebbles and twigs so it was just the snowman piece, and ate it. Even though it didn't seem like much, his HP went up by 45, and that would have to do.

After Sans dodged the water whip, he closed his eyes and said, "until suddenly, everything ends." At this, chills ran down Percy's back even as the next attack came out.

Bones stuck up out of the ground all around and started coming toward him. Just a few platforms lay on top of the bones, which he'd have to jump across to for him to stay unhurt. When Percy jumped off the last platform, a bone connected to the ceiling hit him right in the face, throwing him off his trajectory to plummet down to the bones.

As Percy fell, on instinct he raised up a few sudden and sharp spikes of water and ice, many of which hit Sans. Just after, Percy fell into the bones below and felt his health drain away.

The two of them were impaled by the other's attacks at the same moment.

The water sloshed to the ground and the bones disintegrated, leaving just the two of them dying on the ground near Papyrus' scarf.

After a moment of shock, Sans closed his eyes and quietly laughed out blood. "heh heh heh..." He opened his eyes, now empty as a void. "that's your fault, isn't it?"

As those last words reached his ears, Percy Jackson felt his soul shatter inside of him, and everything went black.

Happy Halloween everyone. ;)