A/N:Sorry guys, I know the Game Theorist's theory about the Halloween Hack saying that Sans is actually Ness isn't popular, but I decided I wanted to tackle it anyway! Anywho, I have only played a little of Undertale myself and watched Dan and Phil play it, and I've watched people play the Earthbound halloween hack. So my knowledge of Earthbound is limited, so if I get some things wrong, feel free to correct me/help me out if need be. I have only recently gotten into Undertale, so my knowledge is limited.

Edited as of 2/16/2018-have watched most of Earthbound and Undertale now. So the story will be better. It's a darker take on Sans and Ness-the original three kids are dead and are staying that way as is canon to the Halloween Hack. Sans/Ness is more embittered, cynical, the whole lot.

But I don't know, in my opinion the idea of Sans being a human from another world kinda transformed/killed is very fascinating. Especially considering I already have Masaomi as a time traveler thrown into another world, this whole crossover theory is very fascinating to me. Anyhow, not even Papyrus in this story knows Sans' true identity, because Sans himself doesn't want anyone to know.

Also, Sans' memories of the whole affair are kinda scrambled from the trauma, so he might not remember everything, but just enough to know he can't hide forever. It's from Sans' POV, also.

Part 1: Unlocking Memories of Dark (Ness); the comedic skeleton who is also a...human?

He was afraid.

Sure, he was ready to save the world, alongside the rest of them.

Ness gazed over at his friends, who met his gazes with determined stares. He could tell that Paula was scared, too, shaking as much as she was. How he wanted to grab her hand and tell her everything would be okay.

Jeff seemed afraid, too-the only one who seemed unaffected was Poo, who was just staring straight ahead.

Ness straightened his cap, still sweating. This was it. He was going to battle Giygas-the monster who'd ruined his world-who wanted to ruin it.

Professor Andonuts was waiting patiently for all of them to get into the machines.

He and his friends climbed into the machines.

"Make sure you take care of yourselves," Professor Andonuts assured them as he strapped them into their time machines. They had to be inside robotic suits, after all, materials that were organic would be torn apart.

Shaking, Ness climbed in, thinking only of fear.

He didn't like being inside this darkened machine any more than the others did, but if they were afraid, they didn't say anything.

He, Ness, heard nothing but the whirring of the machines as it began, throwing them forward into the dimension where he would be able to defeat Giygas.

Visions of his life flashed through his head-all the enemies he'd fought, the town of Onett, Porky, his brother pokey, his father, his mother, his sister, Paula.

So this was where it all began.

The young boy tightened his fists and held on for dear life.

It was then that he realized that something was wrong. For some reason, his machine wasn't working properly. The lights were blinking in the wrong colors.

'What the-' He thought, before feeling something hot and painful come over him.

Something came flying at him inside the machine and hit him...then he lost consciousness..

Sometime later, or what felt like a long time later...he awoke.

It hurt like hell...his head was killing him.

Groaning, Ness turned over, only to find himself buried in something cold.

Sputtering in disbelief, he shook himself off, gasping at the sight of the snow covering him.

"Snow...?" He grumbled, in a strangely hoarse voice, before sitting back up.

As he glanced around, he saw that he was surrounded by nothing but snow. This wasn't where he should be.

He turned around and inspected the time machine, noticing that it was horribly distorted and smoking red, though now covered in snow.

Panicking, he ran back to it, noticing that the buttons were all warped. Pushing every button proved useless.

He was stuck...wherever he was.

He glanced at his hands and he gasped. His hand was now pure bone.

How the hell...did that happen?

He let out a terrified scream as he took in his body.

He was...dead?

But how!

He screamed for his mother, for his parents, for anyone, but none of them answered.

No sign of Paula, Jeff, and the others...they could be dead for all he knew.

Why was he dead? And why was he a skeleton?

Then a figure approached him.

"Are you all right, young one?"

"Who are...?" Ness asked, looking up at the strange skeletal figure.

But it all faded to black.

My eyes shot open as I sat up.

No sign of Giygas, of the kids I'd once known.

That had all been a dream of the past.

A past I can't go back to.

I stared at my skeletal hands and sighed.

"Relax, pal, you're not Ness anymore, he's dead..." I mumbled to myself, glancing over at Frisk, who was asleep near me. They hadn't seemed to notice my nightmare. Good thing.

After all, Frisk wasn't the only human who had wound up in the Underground accidentally now, were they? Not that I've ever told them that.

I've never told anyone my past.

Even I don't remember all of it.

It all happened so long ago.

I scratched my head and decided to go back to sleep, figuring a monster needs his rest. After all, that stupid flower could show up and try to attack Frisk. But my eyes remained open as I stared at the wall. This isn't like me.

Normally, I'm the most jocular skeleton in the whole Underground. But that nightmare...it unsettled me and made me show vulnerability. It was literally spine-chilling!

Ah, that's more like it!

'I'm not that person anymore. To hell with that world. And that place. I decided long ago, that I'm never going back. Not even my brother knows about my true identity.'

Still, as I gazed at the ground, I had to wonder to myself...what had happened to all of the others? My friends...no, Ness's friends. The second I became Sans, I swore I would forget all of it. That constant guilt...that made me feel like I'd ditched all of them-my sister, my mom, all of my friends.

Had their world been saved?

Had they managed to defeat Giygas?

Would they ever know what had really happened to me?

My memories of it were fading. It seemed like the longer I spent in the Underground, the more my memories of my previous life were fading away.

'I'm not Ness anymore. I'm Sans. No more thinking about it, Sans. You have more important things to think about. Like protecting this world. I don't care about that anymore. I don't need to go back.'

If those people could see me now, as a skeleton, they'd probably scream.

Oh well, they didn't mean anything to me anymore.

Did they really not?

'Then why did you have that nightmare, Sans? You're just escaping from your past...' An inner voice taunted me.

I ignored it and fell back asleep.

I know I can't keep running away forever.

Sooner or later, all of them will have to know the truth about me.

But I don't want them to know.

I don't want them to know that I failed a long time ago.

That I used to be a human.

That I...failed all of them!

It still hurts.

But hey, I'd rather smile and enjoy the here and now than focusing on the past.

I can't change that.