S.P: Real name: Swappy, they are the last fallen child, is a teenager that normally has a aggressive neutral attitude, people normally thinks that they is the first fallen human for their similarities.

Temmie: is a cyborg made by the royal scientist undyne, the soul of Mettacrit posses it unconsciously, it acts on instinct but still has the bad spelling of Temmie and the glamor of Mettacrit, in addition to his fraze: Darling

Monster kid: one of the dreemur bothers, he wants to be a part of the royal guard as same as his brother Asriel, in a genocide rout he dies in front of Asriel, and this one escapes to tell it to asgore.

Asriel: The older dreemur brother, he wants to be a part of the royal guard as same as Monster kid, you have a date with him in a pacifist route.

Asgore: he's the ex king of the underground, thanks to his friend relation with papyrus he told toriel to make him the new king, now he works for him being the leader of the royal guard, you can't fight against him in a genocide route.

Toriel: the ex queen of the underground, he like to make costumes for her friend Alphys, also likes to bake cakes, her is undyne helper, and her will fight you in genocide route as THE EX QUEEN, in that battle her will use her queen clothes.

Alphys: a cosplayer that likes the anime, normally her makes weapons that add powers to her, like a Magic wand, in genocide route her will become angry for kill undyne and use a costume referencing her favorite Anime Dragon Cat.

Napstabot: a robot mady by undyne with the soul of one of Mettacrit older cousins, before take the first fallen human soul, he was a friendly robot, he trurn so diferent after take the soul.

First Fallen Human: Real name: *****?, information is actually unknown.

Story: https://gamejolt.com/p/k-swapshift-update-m7hnzqg8 (the story is almost the same to the old version one)