The king of the subsoil.
Queen neglects Asriel and lives in the subsoil.
Helps Gaster in the True Lab.
Papyrus === Member of the royal guard.
Alphys === Second member of the royal and new guild of Undyne.
Boss of the royal guard. If you are on the neutral route and murdered Papyrus or Alphys she will remember it and become Undyne the Undying.
Mettaton === If you kill Alphys Mettaton appears in the CORE and becomes Mettaton NEO.
Napstablook === Napstablook is happy.
Muffet === Collaborates with Grillby.
Gaster === Real scientist. Studies a suesor for human souls.
The 6 human souls === These became floweys that you will find around the world.
frisk He changes roles with chara being who murdered toriel and asgore
Monster kid He trains to become a royal guard