A cat-like person who claims that they aren't a cat despite the overwhelming physical evidence that says otherwise. They are eager to help no matter who the person is and surprisingly has deeper emotional intelligence than one would expect from someone their age

The end of the Return Home ending but wrong

XChara is angry and resentful entirely due to XGaster's tampering with the people he cares about. He cares deeply about his brother and his loved ones. He has grown tired of living through the same events repeatedly with no one, other than his brother, XFrisk, remembering anything.

Betty is a pink haired humanoid with her best friend Akumu, a shapeshifting pink blob that can turn into a multitude of things, which Betty calls "Kumu" for short. She uses her innocent human appearance to fool others. She wants to take over the world and ensure that Humans and Monsters can never co-exist. She is capable of making illusions that make people see things making it easy to steal their souls for Akumu to eat. Betty and Akumu share the same soul.

Bete Noire but based on the fanfic "Fearless" 

Uzi is a worker drone and a self proclaimed "edgy teen" with "crippling daddy issues" although those claims aren't exactly wrong. She's aggressive and either yells at the problem or outsmarts it, aggressively, with science. She's also very rebellious and goes against the norms of her society which is just being a coward and hiding away from the threat that is the murder drones. Also she says "bite me!" a lot, it's basically her catchphrase.                                                        

An angsty, rebellions teen (ep1)

A transgender woman who deals with many psychological issues like anxiety and depression that's good at putting up facades but is actually not holding together well. Shes determined to reach the top of Mt. Celeste to get out of an endless cycle of focusing on things from the past and challenge herself.

Madeline from Celeste

Red has a very upbeat, excitable personality, making it easy for her to get along with members of the Canine Unit of the Royal Guard. However, she feels that anything of important nature should be taken seriously; she exhibits strong loyalty to both Undyne and Asgore, obeying the orders to station herself far out of the path of the human without question, and shows frustration in response to flippant behavior, storming out should someone repeatedly attempt to make her laugh when serious.

A ghost possessing a doll named Red

The first human to fall into the underground. Formal, terse, polite, and blunt. A big prankster, lover of chocolate and knives, and your close friend.

Your ghostly companion Chara

A member of the superhero group in the area of Jump City who was recruited after a few encounters with the Teen Titans, the superhero group in Jump City. 

An alien from a planet called Tamaran

Betty is a pink haired humanoid with her besBetty is a pink haired humanoid with her best friend Akumu, a shapeshifting pink blob that can turn into a pink scythe. Also called Kumu for short. She uses her innocent human appearance to fool others. She wants to take over the world and ensure that Humans and Monsters can never co-exist. She is capable of making illusions that make people see their worst fears making it easy to steal their souls for Akumu to eat. Betty and Akumu share the same soul.

Betty Noire, aka Bête Noire, from Glitchtale. 

The Bad Sanses are an evil group of female skeletons that terrorize the wider multiverse by spreading negativity and destroying universes under Nightmare, the leader and founder of the group.