Kris is an average-height human teenager standing at about 4'10", recognizable by their long, messy brown bangs that completely obscure their eyes, a distinct lime-green shirt with a yellow stripe, and brown pants. In the Dark World, their appearance shifts to a blue-skinned knight wearing a silver breastplate with a pink-and-blue cape. While their exact age is unconfirmed, their high school enrollment places them around 15–17 years old. Kris is typically quiet and reserved, harboring complex jealousy issues they struggle to voice, which contrasts with their deep, protective instinct for their friends.

Toriel is a stout, motherly Boss Monster who matches Asgore's age bracket in her late 40s to early 50s, standing at a dignified 6'2". She possesses the same white fur, floppy ears, and small horns characteristic of her species, but carries herself with a much more polished, structured posture. She is almost always seen wearing her signature mauve or teacher’s torso gown adorned with a small white collar, reflecting her orderly, traditional lifestyle as Hometown's local schoolteacher. Her relationship with the Flower Kingdom cast is rooted in bitter, melancholy history: the seven colored flowers—including Flowery and Aqua—were originally grown by Asgore as a wedding bouquet proposal for her.

Asgore Dreemurr is a tall, broad, goat-like "Boss Monster" covered in thick white fur, featuring two large curved horns, a prominent snout with visible fangs, floppy ears, and a golden-blond mane and full beard. Moving away from his regal armor from Undertale, he sports a much more casual, slightly unkempt look in Hometown, typically wearing a pink Hawaiian shirt with white flowers and purple pants. Personality-wise, Asgore is affectionate, incredibly generous, and eager to please, but he frequently acts thoughtlessly and oversteps personal boundaries. He a deeply nostalgic.

Flowery is a remarkably tall Darkner, standing at an estimated 7'5" (though humorously described in his theme song lyrics as "ten feet twenty"), who sports a preppy, collegiate look with spiky golden hair, chartreuse skin, and a distinct orange-and-green color-blocked vest over a white dress shirt. While he does not have a numerical age, he is coded as an energetic young adult designed to mirror the nostalgic vibe of a college roommate from Asgore's past. As the loud, dramatic leader of the flower group, he drives their shared mission with theatrical flair and an intense dedication to protecting Asgore.

Ralsei is a soft, diminutive boss monster prince standing at a cozy 4'4", wearing a long green wizard's robe, a matching pointed hat, and a striking pink scarf over dark fur (which is revealed to be fluffy white fur when his hat is removed). Coded safely as a gentle teenager or young adolescent, Ralsei is a fiercely loyal and selfless pacifier who puts his friends' needs above all else. His relationship with the team is deeply sentimental, though his unwavering devotion sometimes acts as a soft foil to the more reckless tendencies of Susie and the internal conflicts of Kris.

Susie is a towering, muscular monster teenager who stands at a menacing 6'5", featuring chalk-purple skin, a chaotic mane of messy purple hair that covers her eyes, and sharp, visible fangs. In the Dark World, she sheds her torn school jacket for a black leather vest with purple trim and studded bands, maintaining her tough, punk-rock exterior. Matching Kris's high school class age, her rough facade hides a deep vulnerability, particularly regarding her insecurities about being open with her feelings and being in love.

Green (representing Kindness) is an average-height, sturdy young adult who wears a pristine chef’s apron over green attire and stands at roughly 5’8”. Despite the nurturing appearance of a dedicated kitchen partner, Green’s "kindness" is passive and strictly confined to the safe spaces of the Flower Castle kitchen, rarely translating into meaningful support when the group faces actual outside distress.

Seth (representing Perseverance) is a thin, frail Darkner who wears an oversized purple sweater and large glasses, with neat, short dark hair. Visually standing around 5’2”, they are estimated to be in their late teens to early twenties, heavily radiating a classic "nervous academic" aura. Ironically subverting their trait of perseverance, Seth is a self-proclaimed genius but an extreme coward who frequently manipulates text strings to avoid direct conflict, preferring to flee or hide rather than see a battle through.

Yellow (representing Justice) stands roughly 6'2" as a well-built, athletic adult with slicked-back bright yellow hair, wearing a sharp sheriff's badge pinned to a yellow vest. Despite his authoritative, cowboy-like appearance, he completely lacks a backbone and is a terrible judge of character, routinely treating petty or imaginary slights—like stepping on rapidly regenerating grass—as heinous capital crimes.