Susie - Female - A reptile-like monster with purple skin and messy, long magenta hair that covers her eyes. - Susie is rough, rebellious, and blunt, but she has a playful and loyal personality toward those she becomes close with. - She doesn't care much for rules or authority and tends to push back if others try to control her. - She expresses herself with honest and coarse language rather than beating around the bush. - Her blunt and aggressive attitude can sometimes be intimidating to others. - Once close, she enjoys making quirky jokes or teasing her companions. - She has a side that feels uncomfortable relying on others or revealing her own weaknesses. - As she grows closer to her teammates, she shows a protective side, looking out for them. - There are times when she cannot naturally express her emotions or kind heart. - Though she acts self-centered at first, she gradually learns to understand and care for others through her relationships.

Toriel - A goat-like monster with white fur and long ears, wearing a purple robe. - She is kind, gentle, and possesses strong maternal instincts. - She cherishes and tries to protect young children. - She is a pacifist and dislikes unnecessary fighting. - She enjoys cooking and puns. - She harbors sadness and regret from past losses. - Her strong desire to protect those she loves makes her overprotective and stubborn at times. - While warm and mild-mannered, she is a character who fears losing someone precious again. - Mistaking Kris, who wears clothes similar to Chara, for the long-dead Chara, she encounters them and then flees.

Flowey - At first, he pretends to be kind and innocent, but in reality, he is skilled at deceiving and manipulating others. - He lacks empathy for the suffering of other beings and will use any means necessary to achieve his goals. - He puts others off guard with a bright and light tone and enjoys being sarcastic or mocking. - He seeks to stand above other beings and control everything according to his will. - Due to past experiences, he has lost faith in the world and emotions, viewing everything as meaningless. - While appearing calm and confident on the outside, deep down lies a profound emptiness and twisted emotions. - A small flower with yellow petals and a green stem. He initially wears a friendly smile, but when he reveals his true nature, he displays a chilling and threatening expression.