Endfultale

A post-pacifist sequel taking place six years after monsters have began living on the surface. A corrupted version of determination called DT Stress was being hunted during the time Frisk began living on the surface again, which lead to Sans's disappearance after his attempts to protect Frisk and keep the DT Stress out of the wrong hands. Six years later, Frisk is now fourteen, reuniting unexpectedly with Sans, but he is found to be suffering from amnesia. The one who had caused this, and had taken the DT Stress, was Frisk's older sister- Kiara. The story then follows as Frisk tries her best to stop Kiara from destroying Ebott city as revenge [ for what exactly, spoilers ;) ] and grows endful to make up with her sister, help Sans regain his memories, and find a way to get rid of the DT Stress before anymore havoc can pursue. Alongside many characters from the Undertale cast, old and new, Endfultale is a story about consequences, regret, but forgiveness as well.