Undertale SansxFrisk- Always Smile

Always smile..

Frisk has promised to never reset, which Sans decides to take her word on. After all Months pass and humans begin to adapt to the changes that has befell them, some more easily then most, so Sans is content with how things are and knows Frisk strives for Monsters to be fully accepted and to keep their happy ending.
But circumstances change and Sans finds himself wishing she had never made that promise.

A/N: This will feature Sans and Frisk in a relationship later. just warning. This is gonna be loaded with angst eventually. Frisk gets really sick.