AU where your soulmate's last words are written on your wrist.
Sans' wrist read "I'll miss you."
He was sure it was Toriel.
She was motherly, kind, funny...what more could a guy ask for? She was sure he was her soulmate as well, her wrist reading "My darling."
A few weeks after thirteen year old Frisk broke the Barrier, Sans asked Toriel out. She instantly agreed. When Frisk was seventeen, the two said their vows and sealed it with a kiss.
Frisk was nineteen when the bombing happened.
She had been making a speech in front of the Embassy when the SBM- Surface Belongs to Monsters, a radical pro-monster group who still wanted to wipe out humanity- blew the stage up.
Three monsters were dusted and six humans died. Frisk was immediately rushed away in an ambulance, Sans hugging his wife as she sobbed.
Later, the two visited the hospital.
"Hey." Frisk rasped weakly.
She knew she was dying.
"Hello, my child." Toriel whispered. Tears were still streaming down her face, no matter how hard she tried to wipe them away. Frisk smiled. "Are you feeling alright?"
"I'm fine. It'll be okay. I'll miss you."
Sans paled as the heart monitor went flat. Toriel looked from her husband to her daughter, at the soulmates. Quietly, she left the room.
"Frisk?" the skeleton asked weakly, praying that he was dreaming. His mind replayed memories of him and Toriel, replacing her with with the human. It fit. "Frisk?! Wake up!" He started to frantically shake her, praying that it wasn't too late.
That they could have a life together.
She didn't.
