NaJ Underhigh "Your Life Story" (AU sanses x Fem!reader) [COMPLETED]

Your name is (Y/n) you have no idea of your past all you know is that your "dad" is W.D. Gaster and your "brothers" are Gaster Sans or Gasts/G and Cross Chara and your "mom" is Arial. You have to go into a new school called Underhigh. Your life was fine and you were happy with that. Through your days in going to Under...