( just a bit of info that'll come into play later. *shrugs* also this is the Percy jackson/undertale crossover, I just changed the name lol.

Papyrus is actually older than sans, albeit acting younger. Paps is a demigod. Paps was the only demigod to join the Monster human war, him having been a human before.

Somewhere in the fighting, he ended up switching sides after realizing that these monsters were different.

He ended up saving a skeleton monster and her month old child.

She ended up dying. But before then she made him promise to protect and take care of her child. He promised that to her.

He had gotten trapped with the monsters. Somewhere in between , he ended up turning into a skeleton monster through his bond with the skelebones. Later on, he made sure that the skelebones knew that he was his brother, even if not by blood.

Frisk is the child of Janus, Roman God of choices. Making Frisk a demigod.)

(Quick a/n: I have read the books, but I can't remember if Camp halfblood was destroyed or not in the final battle of Heroes of Olympus seeing as its been ages since I last read it. Imma just go with yes, and state that this takes place after the camp is repaired.)

Percy didn't know what he was expecting.

Ok, let's start from the beginning.

The day started like any other day. Everyone was training, talking, other things he didn't want to list, ya know. The usual.

And then Rachael showed up , freaking out about a prophecy. It took an hour to calm her down enough to get her to tell us about the prophecy.

When she calmed down enough, she repeated the prophecy, 'An ancient race bound to time will walk the Earth once more when the sounds of shattering is heard. Those of the sea, sky, underworld, and earth will all turn heads as sound causes the Earth to shake. Magic will radiate around the world, unleashed by a spell once forged now broken. It will bring things unimaginable to light as beings once lost in the mist will roam once more.'

The prophecy was confusing. It didn't sound like a prophecy for a quest... No, it sounded like a warning. What kind of warning no one knows. They'll have to find out soon enough....

Weeks later...

Percy sighed, a frown on his face as he sat on the beach in thought. The sea was calm, sparkling in the early morning sunlight. Something wasn't right... He didn't know what it was, but something was going to happen today. He could feel it.

He heard a sigh behind him," What's bugging you, seaweed brain?"

He felt a small smile form on his face at hearing Annabeth's voice, him turning towards her. His smile faded at seeing the look of worry on the other's face.

He looked back towards the sea, only saying two words," The prophecy."

He heard her footsteps in the sand before he could tell that she was sitting next to. She set her head on his shoulder comfortingly before she replied," Ah.... What do you think it means?"

Percy shrugged the shoulder that she wasn't leaning on, indicating he had no clue," No idea.... But I have a growing suspicion that things are about to change."

Annabeth nodded," For better or for worse, it depends.."

They soon settled into a comfortable silence, Percy having wrapped his arm around her.

And then that silence was thrown away when a loud shattering sound echoed through the air, the ground starting to shake. It wasn't a bad shaking though, just enough to be noticable.

They both stood, each reaching for their weapons as they glanced at eachother a split second before bolting it to camp.

Sans was tired. Oh so tired.

The kid had just went through the underground, complete pacifist route this time. But that wasn't why he was tired.

No, the reason he was tired was because his night terrors got more intense these past few weeks. And they weren't of the human or Chara. No, they were some kind of Monster. Not the underground types of monsters.

It was one that seemed more cruel, as if they came from the evil half of the monster population. It was large, having the body of a human while having the head of a bull.... Or something like that. It was attacking humans. Teens to be exact. In Greek armor. It was really weird.

There were other more terrifying ones, but he'll bar them from memory.

He had heard once long ago that there were two types of monsters. Monsters created out of MALICE, and monsters created out of HOPE. The ones created out of MALICE couldn't be seen by normal humans. Only by special humans. Then, the ones made out of HOPE could be seen by all humans.

If what he heard was true, then the humans picked the wrong monsters to have a war with.

Then again, only monsters made with HOPE can absorb human traited souls... And , if he remembered correctly, the humans were scared of what they thought could happen.

Sans sometimes questions human logic.

The skeleton hummed , slowly walking up to the cave entrance. Out there, on the cliff, stood every boss monster.

Toriel had her paw on Frisk's shoulder, all of them watching the sun rise.

Sans grinned, walking up next to his brother while humming," Heya bro. "

Papyrus smiled happily at sans," Brother! Can you believe it?! We're on the surface!..... What's that glowing ball of light floating in the sky?"

Sans chuckled," Paps, that's the sun."

Papyrus nodded seriously," Makes sense!"

Sans's ever permanent smile grew slightly," I guess I put some light onto the question."

Papyrus groaned, stopping his foot while shouting," SANS NO! NOT AT A PERFECT TIME LIKE THIS! WHY MUST YOUR PUNS TORTURE ME SO!?"

Sans chuckled," Bro, you're smiling..."

Papyrus huffed," I know and I hate it!"

Most of everyone was chuckling at the friendly banter between the skelebros, all enjoying the moment.

Sans' hands clenched in his pocket, a dull feeling filling him. The same ol' same ol'...........

Just a repeat of the timelines before. Wash, rinse, repeat.... When will the kid just... Let everyone have their happy endings and get to enjoy them?

He was snapped out of his thoughts by his brother running down the hill, Undyne following closely.

Sans chuckled, speaking up," Imma go after him. See ya." Sans winked at Frisk before walking towards the underground instead of down the hill, pulling his 'going the wrong way but somehow always getting to where he needs to be' stck.

Sans sighed once he was fully out of sight, leaning against one of the walls. He set his hand on his skull, taking a deep breath.

.... Heh, it really isn't a lie when he said that the surface didn't appeal to him anymore.....

He should go find Papyrus. Hopefully nothing bad will happen...