Outset

It was a normal day, like any other day. Where Serina and I would either just train with each other, or just anything else other than that. And here, we can see that both of us were training, when suddenly.

"Hey, is there something shining in your eye sockets, or is it just me?" Serina, who noticed that something was glowing from within Jin's head.

Jin stops his attacks,"ah now that you've mentioned it, my head does seem kiinda itchy in there." He then proceeds to scratch the inside of his skull, but as Jin puts his hand inside of his skull from his right eye socket to scratch the part where it was "itchy", but he felt something else.

 "hey what's this weird soft marble object that im touching" out of curiosity, he pulls the weird object out within from his skull to reveal a glowing red orb.

"I don't remember this thing shining this brightly when I extracted it from Sans' soul" he does the iconic thinking position.

"So what are you going to do to it?", his creation; Serina asked as she approaches Jin.

"nghhhh no idea, maybe I'll just put it back in that currently empty soul, maybe something will happen.", he replied.

 "No, that thing will definitely attack us."

"nahh we'll be fine"

"Fine, if you insist"

"then here we go!"

Jin quickly barges in his home to put the red orb in the empty soul of Sans, while Serina follows from behind.

"Alright, chair decoration, get ready to have a soul again." Jin mocks the empty body of the previous insanity sans, which has been lying down on the couch for a long time already.

He tries to fuse the red orb with the soul, but it did not work.

"oh yeah, this soul needs to be NOT empty so i can fit this..thing.. I'll just call this the determination essence" said after his failure on trying to fuse the red orb with the empty skeleton husk that was on his couch.

"so i have gained a new mission, which is to somehow make this determination essence turn into a soul, or atleast try." Jin thought to himself.

"alright girl, we're doing this today. follow me!" He exclaimed.

Jin and Serina went outside to test out various things to turn the essence into a soul.

"Are you really sure this is fine?" She asked with a worried tone.

"pff it'll be fine, it's not like he's gonna turn into some abomination or something.", but he laughs it off.

and with that, both him and Serina tried to form the red essence into a soul.

* a few minutes later..

Serina manipulates the red essence and tries to-"stop stop stop, you're making an entirely different thing!" Jin stops her before she could complete what she was doing 

"Sorry..! I will try again."

though it was probably a tiny bit too hard than they originally thought.

* after some times has passed.

"turn into a soouul... alakazam!" then, a large explosion occured and caused the surrounding area they were in to be filled with thick red smokes.

"I know you were the one who wanted to do this in the first place, but do you even have any idea what you're doing?" Serina said disappointingly.

then before they know it, hours has passed. The both of them did a lot of stuff just trying to shape the red essence, so they decided to take a rest.

"Shouldn't we take a rest? It has been quite a while now.", Serina said, they looked exhausted after trying to shape the red essence into a soul. Meanwhile Jin seems completely fine, he didn't break a sweat.

"yeah i guess ur right, ima lie down for a bit or something now"

as he was saying that, he went inside and put the determination essence on the empty Sans' head because it seemed convenient to him, plus he liked how it floats.

Jin then sits down next to the so called chair decoration,which was at the farthest side of the couch, "ahh, nothing like sitting on your couch after a long tiring day."

"So will we try again another day?", Serina said as she sits next to me.

"yeah sure, not like i have anything else to do in this place."

As the both of them continued their conversation, the hollow body of Sans absorbs the determination essence from the small cracks of the skull, making a small red radiance around him.

"Hey Jin, look beside you!" She warns her creator of the glowing radiance besides him.

He turns to his right to see what Serina was talking about "oh hey, this thing's glowing.... wait what happened"

 "Just to make sure, that glowing thing was on you, right?" 

 Jin seemed to be preoccupied after seeing this.

in fact, he felt something a bit weird. the feeling like there was suddenly another him, Serina was tugging his jacket hard, waiting for an answer.

 "well, why don't we.. go out for a bit?" Jin said, nervously.

"Oh, alright then"

Serina responded, so they went out to a nearby timeline to relieve theirselves from home.

.

.

.

And so, a new entity emerges from the dark, with a large grin on their face.