Chara Dreemurr is the last human that fell in Underground before the protagonist, adopted after they fell from the surface by Asgore and Toriel. They live in Snowdin with their brother Asriel, and play a supporting role in the story. You encounter them in the beginning of Snowdin. They take the role of Sans in Storyshift.
They have 1 ATK and 1 DEF, like Sans does.
Chara is a human child around the same size as the protagonist, a bit older than Frisk, having the same height as them. They have light brown hair, red eyes and rosy blushing cheeks. They wear an unzipped light lime jacket over a white t-shirt, black pants, and boots.
Chara cares a lot about monsters in Underground, especially their family, which they consider to be the coolest.
They like to tease Frisk, who Chara calls "pretty mirror" due to their physical resemblance, and Asriel, calling him "Rei", saying often that he's cute and that they are cooler than them, even though Chara considers Asriel the coolest monster in the Underground.
Despite their teasing nature, Chara can be easily offended, for example when Frisk says that Asriel is cooler than them. Chara also has a serious side, they are conscious that monsters are delicate and are determined to save them.
They go to Grillby's a lot, petting the dog squad and they like chocolate quite a lot. They also like to prank people with ketchup.
Chara, being born as what other humans on the surface consider a "demon", or a magic-wielding human, can perform magic. Not much is known about their complete magical capabilities, but they have been seen to use shortcuts, similar to Sans. And in their room, we encounter sentient vines which may indicate the use of plant magic. However, it hasn't been confirmed whether or not they have the ability to magically summon knives. As of now, that ability has been deemed as a Headcanon.
As a human, Chara possesses Determination, which raises their abilities. Although they have less Determination than Frisk, they are still aware of the resets.
Chara plays a supporting role in Storyshift. They are very happy when they meet Frisk, starting to follow them in their journey to Snowdin, giving them advice and teasing them. Chara refers to them as "pretty mirror" or "partner".
Just likes Undertale Sans in the genocide route, Chara grows to hate Frisk as they kill all the monsters, including their family (Asriel, Asgore, and Toriel). They make a final stand at the last corridor before they go to confront the king. Chara uses the power of their Determination to fight them while dodging their attacks. Eventually, Chara grows tired and Frisk gets a hit at them with their knife. After they die, Chara summons their remaining strength for one final attack. They then come to the fact that they are going to die, but not before berating Frisk for being a coward, a traitor, and for being a monster in both ways. Finally, they drop dead and Frisk continues to confront Sans.
Asriel is Chara's adoptive brother. They love Asriel a lot, caring about him and protecting him when it is needed. They consider him the cutest and coolest monster in the Underground, and they do not want that any harm is done toward him, as shown when they are worried about Frisk's behavior.
Chara hasn't met Papyrus face-to-face, but has spoken to him. One night, Chara grabbed their vine-cutting knife and ran from home, going all the way to the door of the Ruins. It is highly implied that Chara was trying to commit suicide, when Papyrus' voice came from the other side of the door. They answered almost on reflex, and spent the next several hours talking, with Chara answering Papyrus' questions as best as possible. On the topic of families, Chara talked about theirs, and (presumably) how he wasn't sure if their kindness was real or a cruel joke; Papyrus mentioned he hadn't seen his "in centuries." By the time they had finished, Chara had come to realize the kindness and trust shown by the monsters trapped in the Underworld was completely legitimate, and Chara had abandoned their previous idea and ran home; the first thing they did was cling to Asriel and bawl their eyes out.
Sans saved Chara when they first fell into the Underground with his magic, as they were fragile back then and never would have survived a fall like that. This led to a brawl with Chara's soon to be adoptive mother, Toriel, as she though he was trying to harm them. Chara was grateful to Sans for saving them and confronted him about this when everyone was gathering together at the barrier.
Asgore (Adopted Father)
Asgore is the royal scientist of King Sans and Chara's father (sort of; Not biologically). He is much like his Undertale counterpart in personality, but plays the role of Alphys. He also helped Undyne when she was hurt and made her a cyborg.
Toriel (Adopted Mother)
Toriel is Chara's mother (kind of; Not biologically). Toriel met Chara when she was going to Sans' castle with her daily report. She spotted Sans trying to ''murder'' (even though he was really saving Chara from the fall by holding them upwards with his magic) a human. She adopted the human and Asriel got along with them pretty well.
To Be Added...