Transported into Swapfell sans as a second personality!?

What...

What the flip?! I thought as I stared at the skeleton.

I was confused, I knew I was sleeping in my bed only to wake up to a skeleton in front of me and when I tried to move my body, it didn't respond to me and then I realized. This wasn't my body!

I saw the body move on it's own reaching out towards the skeleton, "hm? Oh good morning sans." I heard and wait...sans? As in the sans the skeleton!? Which sans was I in? I wondered as I heard baby sans giggle a little bit.

I tilted my head and continued to watch, I guess I'm stuck here..I thought a bit annoyed and curious as to what au or original this was.

I know I didn't know too much about undertale and the aus because all of them were so different.

I knew some of the names, like undertale, underswap, underfell, swapfell, fellswap, and the other different swapfells and fellswap.

Then there was outertale, outerfell, dreamtale, horrortale, killertale, dusttale, xtale, abysstale, quatumtale, handplates, gztale, and there were too many for me to remember and name them all. But there are a few others like fresh, error, ink, and some others like Geno and reaper.

Hmm..I wonder who exactly this sans is and why am I here in his body. I know I can't move.. and I know this isn't my body since the sans is still here and all.

I'm glad I didn't accidentally take over baby sans, that would be a horrible thing on my conscious... I let out a sigh and the baby stilled and caused the older, who I can guess is a papyrus since I couldn't make out his face clearly, moved closer and sounded a bit concerned.

The baby sans started moving to look around and I got a glance of the house that they were in, huh an interesting home they got. I thought.

Then over the next few years being stuck in baby sans, I learned some things, one, sans can hear me, two, I can actually took over the body and me and sans can switch places, three, I accidentally started teaching baby sans how to use his magic early, four, I think I'm supposed to be sans second personality or conscious or something.

"Morning sans." I said as sans woke up from his nap while he waited for his brother.

"Morning other me." Sans thought back to me. We can also communicate to each other by thinking so sans didn't have to seem crazy by talking out loud.

We haven't told papyrus, our older brother about me just yet...we were waiting for the correct time to tell him about me.

The sans got up and started to get ready and had some trouble doing so but managed to get ready in the end.

It took some more time before We heard papyrus moving to our room and we waited. We liked to keep papyrus on his toes so it would be harder to catch him off guard.

So sans hid and waited for the opportunity to strike.

The door opened and sans launched himself at his brother how caught him in mid air. "Aw no fair paps! I was so close this time!" Sans said pouting.

"Heh sure you were bro, sure you were." Papyrus said and picked sans up and headed downstairs to make something to eat for the both of them.

After they finished breakfast, I decided to ask sans a question.

"Hey sans...do you think it's time?" I asked him and he tilted his head looking thoughtful.

"Hmm...I guess it is time..after all, paps needs time to get used to there being two me's." Sans thought and looked at his brother.

"Paps?" sans started out.

"Hm? What is it bro?" Papyrus's said looking back at his younger brother.