RWBY x Undertale crossover. What can go wrong?

Nothing! That what can go wrong! Now let get into this!

A bright light fill a room and drop a group of random people on the floor. Everyone groan at the sudden force of the landing.

"Ruby/Papyrus! Are you okay!?" Scream out two concern voice.

"I'm okay!" Responded two voices.

"Is everyone okay?" Ask a little brown hair boy.

"I thinks so." Ozpin answer as he look over everyone.

"What just happen?" Ask Ren calmly.

"I don't know, but before we do anything, let introduced ourselves so we can have better commuted better between ourselves. Who want to go first?" Said a goat man in Hawaiian like cloths.

"That is a good idea. Allow me to go first, My name is Ozpin and I'm the headmaster of Beacon." Ozpin said as he took a sip from his mug.

"I'm Ruby Rose and this is my dog, Zwei." Ruby said happily as she show her dog.

"And I'm Yang Xio Long, her older sister." Said a blond woman as she stood close to her sister.

"I'm Weiss Schnee." Weiss introduced herself with a small bow.

"Blake Belladonna."

"I'm Prryha, nice to meet you all."

"I'm Nora and this my best friend Ren!"

"Nice to meet you."

"I'm Emerald and the guy next to me is Mercury."

"Yo."

"I'm Sun and this is Neptune."

"Pleasure to meet ya."

"I'm Glynda Goodwitch."

"I-i'm Velvet."

"Okay, now who are you guys?" Ruby ask as she stare at the different species between them with curiosity.

" I'm Frisk." Said the brown hair boy from earlier.

"I'm San."

"I'm the great Papyrus!"

"I'm Asgore. I'm an ex-king."The Goat man said as he nodded to Ozpin.

"I'm Toriel, Frisk guardian." The gaot woman said polity.

" I'm Undyne and this my girlfriend Alpys." Said a red head blue fish lady.

"H-hello."

"Hello deary, I'm Mettaton~." Said a black hair robot.

Yang pull Ruby closer to her when she saw him.

"I'm Muffet, Frisk girlfriend." Muffet said as she wrap Frisk up in webs suddenly.

"Is that some sort of spider thing?" Weiss ask with a sweat drop.

"Nah, she just like to wrap Frisk up. It kind of messing sometimes." San said with a shrug.

"Anyway, let get back on topic. Why are we here?" Ozpin said as he took another sip from his mug.

"I brought you all here to watch your future." Said a man as a TV screen turn on.

"Who are you and why did you brought us here!?" Undyne demanded as she try to summon her spear, but couldn't.

"I know about your violent nature, so I took all you weapons and powers away to prevent a fight from breaking out. And Undyne, I'm not above of hurting those you care about to get you to stop, so watch yourself young one, or face my wrath." The man said with a shrug.

Undyne look ready to attack, but Frisk step up.

"I understand the precaution use against us, as some of us may attack on impulse, so I promise we won't cause to much problem for you." Frisk said as he bow to the man on he screen.

"When did he escape from the web?" Sun ask.

"Don't ask, it safer to not question his ability at this point." Asgore said with a sigh.

Sun rose an eyebrow in question, but didn't push it.

"I accept your word Frisk. Anyway, I'm Leo, a god. I borough you all here to watch about the future. It about San successor." Leo said.

"My what?" San's ask with an shock expression.

"Successor. You have someone who will have your powers. On the why and how, you have to watch and find out yourself. I just brought you here to watch him in action with you power." Leo said with a smirk.

"Anyway, I got things to do, so see ya!" Leo said as the screen went dark.

Everyone stay silently, letting what just happen sink in. Finally, one of them spoke.

"I guess his air time just crash." Sans said. Papyrus groan at his pun. This was his worse yet!

"I believe we should watch what he wanted to show us." Ozpin said, ingoring San attemp at a joke.

"I think it pawssible." Yang said as she hold Zwei out for everyone. Sans, Toriel and Frisk chuckle at the pun she just made, but Ruby just sigh in saddness.

Everyone was starting to wonder if this going to be a common thing from now on.

"Is everyone ready?" Frisk ask as he and Muffet snoggle on the couch.

"The great Papyrus and friends are always ready Frisk, so ypou don't have to worry about us!" Papyrus said with a puff of pride, Sans just roll his eyes playfully at his brother antics.

"I beleive we are too." Weiss said, annoy but Papyrus screaming.

"Okay then, without further and do, let begin the show!" Frisk said happily as he hit play on the remote.

It was a small rainy afternoon. The sky was cover with grey clouds, the people were rushing to somewhere and the pets were napping.

But, a lone boy was running toward the woods in the small village.

"Ah, that must be the boy we are watching!" Papyrus said happily.

"It seem so, but why is he running?" Toriel ask with a frown.

"I'm sure it nothing." Undyne said with a wave.

"Why do the grimms always have to chase me!?" The boy cried out as he duck under a Beowolf swip.

"I stand corrected." Undyne said with a swetdrop.

He then jump to the side to avoid a Nevermore feather barrage.

"Grimms? What that?" Asgore ask with a rise brow.

"No one know for sure what the Grimms are, but we do know they don't have souls and are attracted to negative emotion of humans and Faunus." Glynda explain.

"Faunus?" Papyrus ask with a head tilt.

"I'm guessing Faunus are alot like Velvet here. Ether they are monster and humans descented, or the next step in humans envoltion. Ether way, it doesn't matter right now." Sans answer with a shrug.

Blake frown at his comment, how dare he assume Faunus were monsters!

"Is that what you guys are?" Nora ask with a head tilt.

"Yeah, that we are call, but we are good creature." Asgore said.

Oh.

That what San's means. Now she just feel silly.

"At least no one getting hurt, cause that would be a bad time for everyone!" The boy said as he made it to the woods and bbe gain to zigzag from trees to trees to make it harder to hit him.

"Did he use one of my favorite lines?" San ask with a rise brow.

"I guess he did brother!" Papyrus said gleefully.

"How can 'Bad time' be your line and does it means?" Weiss ask sceptically.

" Trust me when I said that, someone going to die." San's said as his left eye glow started to glow blue with fire coming out of it.

Weiss gulp in fear, while everyone shiver at his meaning. Frisk flinch to his bad time with San's in one of his RESETS.

"So don't ask question you wan an answer to." San finish calmly. Papyrus snake Sans on the back of his skull.

"Stops caring the humans brother!" Papyrus scolded.

"Heh, sorry bro. Just had to do it." San said with a chuckle.

Everyone were relieve that the tension change back to normal, and praise Papyrus for it.

"Did you felt that power from him?" Glynda ask quietly, she still shaking in fear at the sudden power coming from San.

"I did. Let not anger him." Ozpin said as he calmly sip his coffee, but his face show an impress expression at the power San show. It felt like it could match the four maidens, if not surpass it, in battle if it came down to it. He may a note to look for the boy who will have his power.

They do not need another villain on a power trip to kill everyone.

The boy trip on a rock and went trumbling down a hill. Once he stop, he try to get up, bit scream in pain as he left arm shot pain through his body.

He look at the arm and saw it was broken with a bone coming out.

"Oh that poor child!" Toriel said with a gasp, she then started to freet over the child, while Frisk just shook his head fondly at his guardian actions. Muffet cuddle closer to her boyfriend as they watch Asgore try to calm an enrage Toriel.

"Should we do something?" Muffet ask.

"Nah, she good. Just give her a moment." Frisk answer as he pop some popcorn onto his mouth.

"On no, I won't be able to hide this from mom." The boy whimper as he try get up again, but was stop by growls surrounding him.

He look around him and saw that more Grimm's seem to surround him.

"That just unfair." The boy said as one of the Beowolf pounce him.

"Oh God someone help him!" Toriel cried out in a panic.

Everyone didn't said anything as they were too worry about the boy safety to comment.

Just as the Beowolf was about to bit him, its body started to glow blue and was launch back toward it pack. Some of the Beowolf in the way were hit and die as some bones came out of nowhere and kill them.

Everyone that knew who have that kind of power, none more then Frisk and Papyrus, turn toward San, who was smirking.

Everyone who didn't know why everyone was looking at San in surprise as they born witness to such power display.

'Was that a Semblance?' Velvet wonder to herself.

"Look like I get to dunk some bad dogs." San said as he wonder if this was a fair fight.

"I'm going to comment on that one." Weiss said with a sigh.

"Oh come on, Weiss so serious?" San ask with a chuckle.

"You did not did what I think you did." Weiss said as her left eye twitch.

"Why? Weiss is cold for you or did it make you want Schnee in disgust?" San said with an even bigger smirk on his face. Yang and Toriel burst out laughting, but everyone groan as some try to hold back an enrage Weiss.

After while, they all mange to calm down and wen back to watching the clip.

The boy turn toward the source of that power and saw a skeleton in a blue hooded and some sort of power was coming out of his eye and hands as they were glowing.

"It not nice to pick on a kid you know. So how about picking on someone who will give you all a Bad time." The skeleton said with a smile on it face.

The Grimm's growl in respond to the challage.

"Heh, I'm going to enjoy this. It been a long time since I got a work out." The Skeleton said as he snaps his fingers and more bones appear out of thin air.

"Where was this sense of drive when we were underground!?" Undyne demanded.

"Somewhere where Papyrus was in danger." San reply with a shrug. Yang nodded in approval, she knows what Sans mean.

No one mess with her family and walk away unharm.

Undyne remember when monster attempt to harmPapyrus for the heck of it almost die from being slam multiple time on the ground.

This was a one sided battle.

The skeleton was taking them down quickly and doesn't seem to tire. If anything, he seem bore.

"Come on, the least you guys can do is think your next attack." He said as he simply side step a feather.

He snaps his fingure and alot huge skulls appear and shoots laser beam at many Grimm's, killing many of them in seconds.

The boy watch the one sided battle in awe.

As did everyone else who didn't know San's power and skill.

San smile widen as he watch himself wining against these 'Grimm's'.

He he, get dunk on you creepy dogs!' Sans though happily.

"Well, that was fun. Are you okay kid?" The skeleton ask concernly.

"Y-yes." The boy reply.

"That good. The name San's." San introduced himself as he pick the kid off from the ground.

"I'm Jaune Arc." Jaune said as he dust himself off with his good arm.

"I hope he get that arm fix quickly, cause he look like he in pain despite his acting." Ozpin said with a frown.

"Always a soft spot for children, honestly, you should settle down and have some of your own." Glynda said with an amuse expression. Ozpin gain an thoughful expression.

" Maybe, but after we take care of a storm that is coming." Ozpin said as he took a sip from his mug, much to Glynda amusement.

Frisk rose an brow at the storm comment. Is something bad going to happen?

"Is your arm okay?" San ask as he stare at the arm.

"Yes. Just need to see a doctor and hope my mother don't have a panic attack." Jaune said sheesply.

"Sounds like a certain goat mother I know." Sans said with a fond chuckle. He stare at Jaune for a while and nodded, he seem to decided on something.

"What are you plaining San?" Ruby ask curiously.

"I don't really know, I'm of the past, so I have no idea what my future self will do." Sans answer with a shrug.

Ruby pouted at his words, much to everyone amusement.

"Hey kid, what is it that you want to do?" San ask casually.

"I want to be a hero, like my father and grandfather, but I got a long way to go before that could happen." Jaune said as he look around, tying to find a way home.

"Hmm, why that?" San's ask with interest.

" I grew up hearing story's of not only my family, but of others that had fought and die for everyone safety. I know being a hero isn't always going to be pretty, heck it may be gruesome, but I want help and inspire more hero's, so the world will be able to move forward with a lighter step. Call it dumb or foolish, but it what I belevie in." Jaune said with an DETERMINATION expression.

"I like this kid already." Frisk said as he though the same, but to bring peace toward monsters and humans.

"I agree, he got moxie, a good trait to have in some case." Mercury said with a smirk at the kid guts and determination.

"I love his fighting sprite! I hope he exceed in his goals!" Undyne said as she felt great at the fighting spirit the kid have.

"D-dear, please calm down. We don't want you getting too excited now." Alpys said, trying calm her girlfriend.

"What a strange group of monster." Emerald mumble as she watch their antics till they calm down and watch the clips once more.

"Your a strange one. But I guess you already know that." Sans said as he walk closer to Jaune.

He stop in front of him and stare straight in the eyes.

"How about I give the tools to achieve that dream." San said with a smile.

"What do you mean?" Jaune ask with a head tilt.

"I live for a long time as a spirit kid, it about time for me to meet everyone once more. But, I want leave something behind before I go. So how about it kid? Care to fill my final wish?" San explain tirely.

"What? How come your a spirit?" Weiss ask with a concern frown.

"I don't know. I guess I was waiting for something or couldn't leave as my soul wanted to stay longer. Ether way, I'm going to the next life soon, so it dosen't matter." San's said as he streaches his bones.

Frisk shudder at the though of San's being dead again. He hated what he did on that timeline and what he saw. Muffet pull him closer, she was told everything by a broken down Frisk, but her love didn't change from what she was told.

"It over now. You don't need to worry of Chara or resetting the world once more." Muffet whisper to Frisk as everyone was discussing what Sans just said.

"I know, but the chance is always there." Frisk answer back as he hold Muffet closer to his body.

"We deal with it when it come." Muffet said as she turn back to the screen. Frisk sigh as he know he won't able to change her mind, so he did the same and had a smile smile on his face.

'I love weird people.' Frisk though happily to himself.

Jaune ponder for a moment before nodding his head. San smile as he grab Jaune shoulder and focus his powers into Jaune. Jaune stated to feel tire as his body felt like it was being massage for some reason.

"Feeling tire? That means it working and my power is combinable with your body. So sleep and let my powers get use to your body. Oh wait, it your powers now." San said with a smile as Jaune fell asleep.

"I guess it working." Yang said as de watch the exchange in awe.

"I wonder how powerful Jaune going to be." Ren said in wonder.

"Only time will tell young one." Asgore said wisely.

"Heh. I guess that it then. Be careful kid, a lot of things going to happen and you may not win. But, if your anything like me and Frisk, you will have friends to fight with. So rest up and get ready to dunk people while giving them a bad time." San said as he took off his blue hooded and place it over Jaune.

"Strange part of all this, you getting my powers kind of make you my son dosne't it? So, do me proud." San said as his body started to fade away.

Everyone had some tears coming down their eyes at Sans final words. Sans shift uncomfortably at the sudden feeling in air.

'It not that sad.' San though to himself as Papyrus hug him tightly.

After everyone calm down, they return to watching the clips.

(scean change)

Jaune woke up in his bedroom. He look around in confusion and saw a blue hoodie hanging on a chair.

"I guess he home." Velvet said, everyone jump as they forgot she was here.

"It would seem so." Ozpin answer.

The memory's be gain to rush back to him and he sigh in relief. He look at his arm and saw it was fix, like it didn't happen at all.

"I guess your power heal him brother." Papyrus said.

"I'm glad. I would hate for the kid arm to be broken." San said. Toriel smile as she watch San action toward the young boy. He action like he was his son already.

" I guess it wasn't a dream then and my parents found me." Jaune said as he got up from his bed and started to put on a different set of cloths. He look at the hoodie and tie it around his waist tightly as it wouldn't fit his small body. He look into a mirror and smile.

Cause in his reflection, his left eye was burning a blue flam.

"He learning his new power quickly." Emerald said in awe.

San gave a proud smirk as he saw him figure out on how to power it up.

"I'll do you proud, so watch me dunk on those Grimm's for you." Jaune said warmly as he walk out the room.

(End ofclips)

Everyone sat in silence at the first clips finish.

"Well, that was a thing." Yang said after a while.

"Understatement." Frisk said.

"I suggest we take a moment to process what we watch." Ozpin said. Everyone nodded in agreement andstarts to wonder around.

'I wonder what next.' San though as he shut his eyes shockets for a quick nap.

I hope you enjoy the first chapter. I'm going to be honest, this may not have started off good, but it was a decent start.

Anyway,review if you like this and stuff. See ya.