XGhaster and his Subjects are attacking and corrupting your timeline.

XMuffet was wrapping up humans and monsters for XMettaton to consume their souls for power.

Undyne decide to follow the two Xtale enemies in the forest, as the others protect Frisk from XGhaster.

You made sure to stay with Frisk to keep her safe from the XTale characters from retrieving them and bringing them to XGhaster.