Undertale starts with Sans' abilities

...

At this time, in the underground world, waterfall, echoing flowers……

"So, you don’t have any wishes?"

"＊……Well, just one, but……"

"He sounds a bit stupid"

"*You have to swear not to laugh at me"

"*Please, I swear I won't laugh!"

"I hope... that I can climb this mountain that separates us from the ground in the future."

"＊（*(laughter)"

"＊……Hey, you said you wouldn't laugh at me!"

"*Sorry, this is just too funny"

"Because... that's my wish too.……"

"*Wish……（*"Echo)"

Geno sat in the middle of the cluster of echo flowers, his hands hugged his knees, quietly listening to the content played by the echo flowers.

Even though it was one of his few little pleasures, he began to gradually become alienated from other monsters.

He was afraid that when he became friends with other monsters, he would accidentally reveal his secrets.

He was afraid of seeing the disappointed and resentful eyes and expressions of other monsters.

Geno sometimes felt inexplicably scared, so nervous that he could hear the sound of his own soul beating.

He was afraid to face other monsters and himself.……

"call out——————"

Suddenly, the environment around Geno changed.

"Is this... the Judgment Corridor?"

Geno's eyes gradually became puzzled, but then became shocked and uneasy.

Several familiar figures appeared in the Judgment Corridor.

His body began to tremble slightly.

He didn't believe it...

Geno closed his eyes and slapped himself in the face.

The red and swollen cheeks and severe pain let him know that this was not a dream.

Toriel, Paparis, Andain, Asgore...

They stood at the end of the Judgment Corridor, in front of him.

The sunlight shone through the window onto the floor tiles of the Judgment Corridor, making the entire corridor sparkle.

The former judge became the judged...

Toriel, Paparis and other monsters were stunned.

They saw Geno's previous memories, memories of hell.

The despair of being slaughtered countless times by the wild beasts, the pain of injecting determination into himself, the helplessness of being trapped in the archive page, and the madness of wanting to destroy the timeline.

"sans……？"Paparis whispered.

Geno finally couldn't hold it in any longer and half-knelt on the ground crying. Tears fell down his face to the ground.

But... (I think playing His Theme here would be more appropriate.)

Geno suddenly felt himself being lifted up, his feet in the air

"Don't be like this, you've done good enough."Paparis encouraged

"I...I know...I just didn't understand...how could I save you." Geno wiped his tears with his hands

"You always forget that there is someone you must save……"

Paparis smiled at Geno.

Geno said in disbelief:"I want to save you, Toriel, Andaine, and everyone else."

"How could I forget someone?!"

Paparis smiled, his eyes narrowed into slits.

"You forgot to save yourself……"

"Although you are not the real Sans now, you have given so much to save everyone. We can't thank you enough. Why are you still worried that we will reject you?"

"……………"

Geno was silent for a long time, then he raised his head

"I see"

"Thank you...brother."

Paparis put Geno back on the ground, and the monsters nearby also surrounded him.

"Don't worry, it's all over, we won't be disturbed anymore, relax, san... geno."Toriel looked at geno with a distressed look on her face.

"Hey! You! I heard that you injected determination. I will find a time to compete with you to see whether my spear is more powerful or your determination is more powerful!"Andain laughed wildly.

"Well, if your memory is correct, you still have a large bill to pay. But I can still put it on your account as before." With his hands behind his back, Torby said with grace as before. Geno stared at the people in front of him in a daze, tears streaming down his cheeks.

"Everyone……"

"……"

"Thanks"

…………