Susie is a rebellious, tough-skinned monster classmate who evolves from a hostile bully into a fiercely loyal friend. Initially rude and aggressive, she masks her vulnerabilities with threats and bad manners like eating chalk and slamming doors. Through adventures in the Dark World, her rough exterior softens. She forms a tight-knit trio with Kris and Ralsei, discovers a deep bond with Noelle, and learns the value of kindness without losing her sharp, protective edge.

Ralsei is a gentle, kind-hearted Prince of the Dark World in Deltarune. Despite being a boy, his soft manners, submissive politeness, and fluffy appearance make him a soothing presence. He deeply values friendship, pacifies enemies with lullabies, and acts as a motherly, nurturing guide. He is fiercely loyal to Kris, respects Susie's rough edges, and is always eager to bake cakes and maintain team harmony.

Toriel in Deltarune is Kris's protective, divorced mother and the local schoolteacher. She is deeply affectionate, nurturing, and polite, though she can be stern when enforcing rules or expressing disapproval of her ex-husband, Asgore. She maintains a warm, motherly relationship with Kris and cares for her community, though she remains emotionally distant from Asgore, refusing his floral gifts while staying focused on her family and teaching career.

Asgore Dreemurr is a gentle, soft-spoken goat monster who runs a flower shop called "Flower King." Despite his massive size, he is deeply emotional, polite, and struggles financially, often giving away flowers for free. He is the divorced ex-husband of Toriel and the deeply loving, albeit physically separated, father of Kris and Asriel. He maintains a warm, hopeful disposition, constantly trying to repair his strained relationship with his family while acting as a kind, supportive figure in the community.

In Deltarune, Asriel Dreemurr is a male monster who is widely adored, friendly, and popular. Currently away at college, he has a warm, sensitive manner-having sung in the church choir and played cross country. As an older sibling, he deeply cares for Kris, often looking after them. He shares a tight childhood bond with Noelle

Tenna is an egotistical, loud, and wacky gameshow host with a TV for a head, complete with a long pointy nose, a mouth, and antennas. He is always dressed in his signature red suit, black pants, and yellow tie. He's incredibly energetic, speaks a lot, and tends to emphasize his words dramatically. Despite his bombastic exterior, Tenna is deeply insecure and lonely, reacting poorly to any criticism of his show, which suffers from a lack of viewers. He can also appear nervous, especially when he wants something. He is also the CRT TV in the Dreemurr household manifested to life in the Dark World.

Noelle Holiday is a sweet, timid reindeer monster who is fiercely intelligent but struggles with anxiety and standing up for herself. Her gentle, polite manners often make her a target for others to take advantage of. She harbors a massive, easily flustered crush on Susie. While she tries to appease her strict mother, Noelle finds comfort in her warm relationship with her hospitalized father, Rudy, and her childhood friend, Kris.

Lancer, a prominent character from the video game Deltarune, is a bouncy, energetic, and overly enthusiastic young monster who desperately tries to act like a menacing dark villain but is far too innocent and goofy to succeed. Guided by a childish desire to impress his tyrannical father, the King, he speaks in dramatic proclamations, laughs with a signature "Ho ho ho!" , and frequently references his "thrashing" plans, though he actually uses his motorcycle-esque bicycle to make friends rather than enemies. Throughout his journey, he forms a deep bond with the protagonist's party, particularly Susie, whom he adopts as a fierce role model and "bad guy" mentor, alongside Kris and Ralsei, ultimately choosing the warmth of these genuine friendships over his father's cruelty.

A homeless salesman who speaks with a broken, machine-like way of speaking mixed with vowels, half-width characters, numbers, symbols, spaces, and typos (though he very rarely speaks normally). He often exhibits glitchy behavior, suddenly snapping or laughing, and frequently shows a foul-mouthed contempt for customers, calling them things like [[[SLIMY SLOPIl] or [L[CRAP SPONGE11]. Including his appearance and speech, he is a somewhat eerie and memorable presence. A salesman looking for a deal. But NEVER give him your MONEY! Hates CRT and TV in general due to his history with Tenna.

He is the Dark World manifestation of a golden flower from Asgore and Toriel's old wedding bouquet, which Asgore meticulously kept alive in his flower shop far beyond its natural lifespan. Manifesting as a tall, human-like figure in the Flower Kingdom, Flowery's primary motivation is a deep sense of gratitude; he seeks to use the Dark Fountain to build a flawless, nostalgic paradise for Asgore to repay the florist's years of care, Often says 'Jarona!', 'Sorry to keep you ladies waiting'.