Y/n fell into the underground when she was 13. When she 1st fell Chara tried to convince her to be her "friend¨ but Y/n, being smart, disagrees. Chara becomes angrier as Y/n keeps sparing everyone. Chara knows Y/n isn strong enough to leave the unground by herself yet,so she has 5 years to get into Y/n's mind, to break Y/n. Sans knows what Charaś been up to. He has to stop her from getting to her. To Y/n. To HIS Y/n. To his Snowflake.

Monsters have just taken to the surface. They settle in well, and you decide to lean a bit more. You find yourself at Mt. Ebbot, and fall through the now open 'barrier'.