That Golden Butterfly {Gaster Sans X Reader}

Chapter 18

There was a small bathroom a few feet away from the operating room, and so I booked it inside. Panting and confused, I looked at myself in the mirror. I was a monster. I was a Neko.
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Warning!
This story may trigger readers who suffer from anxiety, depression or PTSD. There are many mentions of domestic abuse, self harm, self loathing, suicidal thoughts and tendencies. If you are easily triggered or bothered by such content, proceed with caution.
~W. D. Girl

A long time ago, a human fell into the Ruins. Injured by its fall, the human called out for help. Asriel, the king's son, heard the human's call. He brought the human back to the castle. Over time, Asriel and the human became like siblings. The King and Queen treated the human child as their own. The underground was full of hope.
Then... One day... The human became very ill. The sick human had only one request. To see the flowers from their village. But there was nothing we could do.

The next day the human died. Asriel, wracked with grief, absorbed the human's soul. He transformed into a being with incredible power. With the human soul, Asriel crossed through the barrier. He carried the human's body into the sunset. Back to the village of the humans. Asriel reached the center of the village. There, he found a bed of golden flowers. He carried the human onto it.

Suddenly, screams rang out. The villagers saw Asriel holding the human's body. They thought that he had killed the child. The humans attacked him with everything they had. He was struck with blow after blow. Asriel had the power to destroy them all. But... He did not fight back. Clutching the human, he smiled, and walked away. Wounded, Asriel stumbled home. He entered the castle and collapsed. His dust spread across the garden. The kingdom fell into despair. The king and queen had lost two children in one night. The humans had once again taken everything from us. The king decided it was time to end their suffering. Every human who fell down there was killed. With enough souls, they would be able to shatter the barrier forever.

Then one day, the royal scientist found a prophecy long forgotten by the monster kind:

A child born to a human and monster, with a golden heart and emblem, will raise above them all, be the most powerful among them all and save the two worlds from clashing. Peace will be brought to the two races and both shall live in harmony.

The king wanted to see this child, had it been born. Luckily, the royal scientist already knew where to find the special one. His two sons, Sans and Papyrus (Yes, fanon Dadster is real here!) knew the child very well.

And so it was, the little child, despite her young age, broke the barrier with her golden butterfly, freeing the monsters of their dark prison. For a few months, monsters and humans lived in peace, until one day...

The little child was kidnapped. The monsters were furious and war broke out once again. The humans were victorious, banishing the monsters back into the Underground.

For 17 years, monsters have been trapped in the Underground, until a human child by the name of Frisk rescued them.
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G!Sans' POV:

"Monsters! Help!"

"They've kidnapped a child! Someone help them!"

"Frisk! NO!"

"Stay determined guys..."

I woke up in a panic, droplets of sweat running down my skull as my soul pounded inside my ribcage.
"It was just a nightmare.. Calm down.."

It's been so long since I've thought about Frisk.. They've been dead for.. For too long. I plopped my head back on the pillow and looked at the ceiling as numerous thoughts came pouring back in.