FULL CAST IS DONE!!!
Some infos about each character:
The humans: They remain in their Underswap roles, as the chronological order of when each is born and fall is specific to the universe. Frisk died a long time ago, we play as Chara
The Floweys: They are a hive mind, through silly, they have a fragmentation of Asriel soul that shows as one trait of his in each Flowey, they have returned to the Ruins, sensing Chara has awaken, interested that they could provide answers to what happened, only to find Chara more confused than themselves, after that they have split into the underground. Every time Chara sees a Flowey it is a different one from the last
Toriel: Does not talk about her past, feeling regret by her decisions as the former queen of the monsters, trying to create a new life exiled in the Ruins, only Napsta knows of her entity as the queen, which he gave her CDs and a radio she likes to listen to. Toriel only wish is to not speak of her after Chara leaves the Ruins. if she is supposed to be exiled from the rest of the underground, Sans is the one who breaks that and can make her feel accepted, forming a great friendship with a lot of bad puns
Napstablook: Quite into modern Dubstep, posts their indie music online, likes to stay in the ruins due to how chill it is, allowing them to concentrate on creating music, sometimes Napsta visits Toriel, in their own house there is a professional competition of slugs in karts in electronics race tracks, number #1 of the underground that everyone takes it seriously and has their own slug (You will be made fun of if you are the last here btw)
Sans: Is a comedian working for Metta, he runs his own stand up in Metta's hotel thanks to the ghosts knowing Toriel, this has allowed Sans to see how big the underground is, in his free time he explores new places and talking to new people, this appears to Chara as if Sans is everywhere
Papyrus: Has joined the Royal Guard as a Patrol for Sans wish to see a human, his job is patrolling Snowdin searching for humans as the brain of the army, for he is not the fighter type he can take his job more easily enjoying doing the walks, specially in the forests, this has allowed Papyrus to have a deeper connection with nature and being more of an outdoors person, he is an excellent builder, and a lot of times you see him it's actually a cardboard, there is plenty of them in Snowdin, everytime you encounter one he comes down from his bridge complex to actually say. Papyrus has built a bridge complex near Snowdin's roof for he being able to move more freely and observe from aware without being watched
Undyne: Leader of the Royal Guard, a nerd who is responsible for modernizing the army with technology, robots and guns, it is pretty hard to anyone talk with Undyne directly due to the hierarchy she constructed for being more of an introvert, you can only see her after you bypass everyone from the Guard, she is openly an anime fan and enjoys fighting robots, which she get inspiration to do the robots of the Royal Guard, her dense inner world might be a bit overwhelming to befriend her if you aren't used to nerds
Alphys: The royal scientist, she is a biologist and paleontologist, loving to dig into the walls of the underground and find old fossiles she can study, decorate, or be transformed into energy, she find dinosaurs pretty rad, Alphys eventually finds ores and gems too, which she keeps some of them and gift gems to her loved ones, she likes how rare and fragile they can be, specially as an act that she is not only a brute and feral creature, something Alphys is anxious of being deducted as
Metta: Is a singer that has blown up in the Undernet and since then managed to appear in TV and form his own brand hotel, giving space for other artists, his music is known for its melancholic themes, the mix of a happy beat with sad lyrics, he is really proud of his history of resilience from being shy shutdown making into an idol, his body was constructed by Undyne in a contract that he would go chase the next human to fall down, because of that, Metta is also in the Royal Guard, chasing Chara in Waterfall's sky
Asgore: A sweet fluffy goat, after Toriel's sudden disappearance, he was the next to have the throne, and was greeted with positive reactions as he is described by some as "Everyone's father" as his best ability is the equilibrium of being a good king and how personal his friendships with people can be, noticing small details about them, Asgore is still not used to being called King, preferring to be called by his name, and is deep down depressed by Toriel disappearance, his hope to find her again is starting to die now