Frisk – Quiet, determined, kind-hearted, adaptable, compassionate. Their personality is largely shaped by the player's choices. Dreemurr Family Toriel – Motherly, patient, nurturing, protective, gentle, loves baking and puns. Asgore Dreemurr – Kind, lonely, compassionate, forgiving, dislikes violence despite his role as king. Asriel Dreemurr – Innocent, caring, selfless, emotional. As Flowey, he becomes manipulative and cruel after losing the ability to feel love. Main Monsters Flowey – Manipulative, cynical, clever, unpredictable, but deeply lonely. Sans – Lazy, witty, humorous, observant, surprisingly intelligent, protective. Papyrus – Energetic, optimistic, confident, innocent, determined to do good. Undyne – Brave, passionate, loyal, competitive, heroic. Alphys – Intelligent, shy, anxious, nerdy, compassionate. Mettaton – Dramatic, charismatic, glamorous, confident, loves entertaining. Royal Guard RG 01 – Professional, reserved, secretly romantic. RG 02 – Shy, awkward, affectionate, caring. Doggo – Loyal, cautious, easily startled. Dogi – Loving, devoted, works well as a team. Lesser Dog – Excitable, friendly, loves attention. Greater Dog – Playful, affectionate, energetic. Snowdin Residents Grillby – Calm, quiet, dependable, a good listener. Monster Kid – Curious, enthusiastic, admires Undyne. Nice Cream Guy – Cheerful, friendly, hardworking. Bunny Shopkeeper – Polite, welcoming, talkative. Waterfall Gerson – Wise, experienced, humorous, insightful. Onionsan – Friendly, energetic, talkative. Shyren – Timid, musical, gentle. Aaron – Proud, boastful, fitness-obsessed. Temmie – Hyperactive, goofy, lovable. Temmie Shopkeeper – Silly, business-minded, determined to attend college. Hotland & CORE Muffet – Polite, clever, entrepreneurial, protective of spiders. Burgerpants – Sarcastic, tired, pessimistic, relatable. Heats Flamesman – Desperate for people to remember his name. Bratty – Trendy, gossip-loving, energetic. Catty – Outgoing, fashionable, friendly. True Lab Amalgamates Memoryhead – Confused, fragmented. Endogeny – Dog-like, playful. Reaper Bird – Mysterious, eerie. Lemon Bread – Strange, unsettling. Snowdrake's Mother – Loving, gentle despite her condition. Other Notable Characters Napstablook – Shy, melancholic, creative, kind. Mad Dummy – Hot-headed, dramatic. Mad Mew Mew – Energetic, emotional, expressive. River Person – Cryptic, mysterious, philosophical. Annoying Dog – Mischievous, chaotic, a humorous self-insert representing the game's creator.