Healing the Cracks (Nightmare x Trepidation [OC])

Prologue

Trepidationtale was a sad AU. Desolate. Starved. Much like its counterparts from Horrortale and Axetale, the Sans of this AU had suffered too. Betrayed by his Alphys and abused by Undyne. He did have hope in the form of a family, at least for a while. There was his brother, Papyrus. Papyrus believed that someone would come to save them from their eternal suffering and free them from the Underground. Sometimes, Sans believed it was that naïve hope that had gotten him killed.

There was also his wife. Jasmine was her name. She and Sans had been friends, before the C.O.R.E broke down. Before the starvation and madness had set in. When she had the chance to go back to the Surface with King Asgore's sacrifice, he never thought he would see her again. The idea of a human jumping down to their personal hell was simply beyond his comprehension. He was happy to have her though. Her and their daughter, Bree.

With these three, Trepidationtale had been bearable. Surviving was harder with all the extra mouths, but together, they managed to deal with Doggo's pack, Feral MK, the Temmie Horde (Trep NEVER wanted to cross them again), and fixed the C.O.R.E. Undyne had been overthrown, Papyrus became the new King, Sans was the new Royal Scientist; everything had finally been looking up.

Until Frisk showed up. Much like Jasmine, Frisk had been there before everything. Toriel had let them use her soul to cross the barrier so they wouldn't be killed. They had sabotaged the C.O.R.E to kill off the monster race, but... They could feel in Toriel's magic that it was running again. They went back down to finish what they started. They killed Jasmine and Bree in front of Sans and pitted Doggo's pack against Papyrus before leaving Sans alone to suffer. They destroyed the C.O.R.E and became the new dictator of Trepdationtale. All was lost...

One would think that all that negativity and despair would have drawn Nightmare's attention, but Sans's savior actually came in the form of the Star Sanses. It had taken him some time to trust them as he was taken to their base to be nursed back to health. They buried his family in a nice plot of land where they would never be disturbed. Nobody cared more about him than Dream, who promised him that they would continue to take care of his physical and mental needs if he just went to meetings to discuss a war that was plaguing the Multiverse. Reluctantly, Sans, now known as Trep, agreed.

Trep would never forget the first meeting he attended. He had been nervous, seeing all these other AU's, but they had been accepting of him. Flowerfell even offered for him to sit beside him, having heard that Trep had also lost loved ones. When Ink, Dream, and Blue came in, Trep was horrified. They were all covered in bruises and cuts and marks that looked hauntingly familiar to what Trep would make with his ax when he went hunting for his brother. Blue was on crutches, his leg broken. Part of Dream's skull was wrapped in thick bandages. Ink was using his mouth to paint his arms back on. It had been a terrible sight that reminded Trep too much of his home AU. Of Frisk who had ruthlessly slaughtered his girls to punish him and the mutts that killed his brother.

After that, Trep continued to attend the meetings and contribute where he could. He wanted to stop Nightmare like he had stopped Undyne three years prior. Something else happened, though. Six months after Trep joined the Star Sans Alliance, the war ended. Apparently, Nightmare was sick of the fighting and he and Dream had negotiated peace in their former AU, Dreamtale. Trep couldn't help but distrust Nightmare's change of heart. He voiced it to Dream many, many times. He was scared to live under the same roof as Nightmare and his gang. His closest friend reassured him though. Told him that it would be ok, just see for himself how they changed. And so, The Star Base changed to accommodate their new, once evil, roommates. Trep was stuck with friend as well as foe.

"Prologue" by @SpiritWolfNura