Undertale Characters & Roles guide screenshot

Characters & Roles

Characters & Roles



This guide provides an in-depth look at every major character in Undertale, including the playable protagonist, key allies, and antagonists. Since Undertale has no traditional class system, each character's \"role\" is defined by their story function, combat behavior, and how they interact with the player. For the playable character, we cover equipment progression and playstyle across different routes.

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1. The Protagonist (Frisk / The Fallen Human)


  • Background: The eighth human to fall into the Underground. The player names them at the start; the canon name is Frisk, but the game refers to them based on your chosen name. Chara is the first fallen human whose name you can also use.

  • Role: Player avatar. The only truly playable unit. Controls every action, from FIGHT to ACT to MERCY.

  • Strengths:

    • - Soul Modes: Your SOUL changes color based on encounters (e.g., blue, green, yellow) granting unique movement or abilities.
    - Determination: Ability to SAVE, LOAD, and RESET. High LOVE (LV) increases damage but reduces empathy.
    - Versatility: Can choose to fight or spare, influencing entire playthrough.
  • Weaknesses:

    • - Low base HP (20 at start).
    - No innate attacks; damage depends entirely on equipped weapon.
    - Genocide route makes you powerful but breaks the world.
  • Playstyle:

    • - Pacifist: Focus on ACT and MERCY. Requires puzzle-like memorization of each monster's weakness to spare.
    - Neutral: Mix of fighting and sparing. Combat efficiency depends on gear and LV.
    - Genocide: Grind encounters until no new monsters appear. Extremely high LV, but many bosses become nearly impossible.
  • Unlock Conditions: Automatically at game start.

  • Recommended Equipment & Builds:

    • - Early Game (Ruins): Torn Notebook (weapon) + Bandage (armor).
    - Mid Game (Snowdin onward): Ballet Shoes (weapon) + Cowboy Hat (armor). Consider replacing with Tough Glove (wait, obtain from Papyrus? Actually it's from Snowdin shop). For armor, Stained Apron from Sans is good.
    - Late Game (True Pacifist): Real Knife (weapon) + Heart Locket (armor) – obtained after Genocide route; if avoiding Genocide, use Empty Gun or Worn Dagger from Alphys's lab.
    - Best Setup (Neutral/Pacifist): Empty Gun or Worn Dagger + The Locket (from Asgore fight) or Heart Locket if you can tolerate Genocide.
  • Team Synergy: Not applicable in traditional sense. However, certain boss fights allow allies (e.g., Sans fights alongside you in Papyrus date, but you control Frisk alone). In the Asriel fight, all your friends appear as SOULs to help you spare.


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    2. Flowey


  • Background: A sentient flower who is the main antagonist. Formerly Asriel's body with Amalgamate determination.

  • Role: Tutorial boss, recurring villain, final boss in certain endings.

  • Strengths:

    • - Can save/load initially, mimicking your power.
    - Petal attacks that circle the screen.
    - Manipulative nature; tricks you into gaining LOVE.
  • Weaknesses:

    • - Extremely fragile after his attacks are learned (can be spared easily in True Pacifist).
    - Loses his determination when you refuse to fight.
  • Playstyle (When Fought):

    • - Neutral Route Boss: Phase 1: Avoid petal spray and wavy attacks. Phase 2: Spare repeatedly, or fight to shorten.
    - Genocide Route: Does not appear as a proper boss; instead, he flees.
  • Unlock Conditions: First encounter in Ruins. Final boss after True Pacifist ending (if you spare him).

  • Team Synergy: None. He is always an enemy, never an ally.


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    3. Toriel


  • Background: Boss Monster, former queen, caretaker of the Ruins. Motherly figure.

  • Role: Tutorial helper, optional boss (or spared friend).

  • Strengths (As Boss):

    • - Fire magic – orbits around the box and rushes at you.
    - High defense; takes minimal damage from weak weapons.
  • Weaknesses:

    • - Cannot bring herself to kill you – if you spare repeatedly, she stops attacking.
    - Low attack power compared to later bosses.
  • Playstyle (When Fought):

    • - Spare Route: Use ACT > Talk > Spare after she hesitates. Do not fight; it leads to a sad ending.
    - Fight Route: You can win, but it's emotionally difficult. Pattern: dodge fire orbs, use best weapon.
  • Unlock Conditions: Meet her in the Ruins. Boss battle at the end of Ruins.

  • Recommended Equipment: None specific; she gives you a cell phone and later pie if you befriend her.

  • Team Synergy: She assists in the Asriel fight during True Pacifist (appears with other friends). Also sends snail pie via snail mail if you maintain the save file.


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    4. Sans


  • Background: Skeleton brother to Papyrus. Lazy but incredibly powerful. Knows about timelines.

  • Role: Comic relief, judge in Genocide route (final boss), minor ally in neutral/pacifist.

  • Strengths (As Boss):

    • - Shortcuts: Instant movement, tricky attacks.
    - Blue eye – attacks that move your SOUL to certain areas.
    - KR (Karmic Retribution) – ignores invincibility frames; deals damage based on your LV.
    - Undodgeable attacks in Genocide (e.g., slamming attack).
    - High damage per attack.
  • Weaknesses:

    • - Low HP (1 DEF, 1 ATK? Actually his stats are 1 ATK, 1 DEF, but his attacks ignore defense).
    - Lazy – does not dodge your attacks effectively (you can always hit him once per turn).
    - Long battle – at LV 20, you must survive 12+ attacks while dealing 1 damage each turn.
  • Playstyle (When Fought in Genocide):

    • - The Impossible Fight: Focus solely on dodging. Attack only when he gives you a turn (after his attack sequences). Use healing items (Legendary Hero). Memorize attack patterns.
    - Karmic Retribution: Do not get hit even once if you can help it – KR damage builds up quickly.
  • Unlock Conditions:

    • - Neutral/Pacifist: Appears throughout the game. Not fought.
    - Genocide: Must kill all monsters in Snowdin and Hotland. He becomes the final boss before Asgore.
  • Team Synergy: He helps you in the Papyrus hangout (Sans is there). In the True Pacifist ending, he appears with other monsters at the barrier.


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    5. Papyrus


  • Background: Skeleton brother of Sans. Aspiring Royal Guard. Enthusiastic and naive.

  • Role: Boss in Snowdin (optional if you befriend him), comic relief, later ally.

  • Strengths (As Boss):

    • - Blue attacks – turns your SOUL blue, forcing you to stay still or risk damage.
    - High HP (around 50).
    - Can capture you with blue magic.
  • Weaknesses:

    • - Does not want to hurt you – if you spare him repeatedly, he gives up.
    - Attacks are telegraphed and easy to dodge.
  • Playstyle (When Fought):

    • - Spare Route: Use ACT > Flirt or Joke, then spare. After enough times he stops and becomes your friend.
    - Genocide Route: You must kill him. He gives a "Papyrus" attack pattern; dodge blunt bones.
  • Unlock Conditions: Encounter at Snowdin Town. Boss fight at Snowdin Forest exit.

  • Team Synergy: If spared, he calls you frequently, gives you spaghetti, and helps in the Asriel fight. He also allows you to access his workshop where you can get the "Papyrus" block puzzle.


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    6. Undyne


  • Background: Leader of the Royal Guard. Fish monster. Dedicated to capturing humans.

  • Role: Pursuing enemy in Waterfall, optional boss (or friend).

  • Strengths (As Boss):

    • - Spear attacks – yellow SOUL mode allows you to shoot back.
    - High speed and aggression.
    - Can turn your SOUL green (you must stay in a small area).
    - In Genocide, she gains determination and becomes Undyne the Undying.
  • Weaknesses:

    • - She can be befriended by water and patience.
    - In neutral/pacifist, sparing her is easy after running or using ACT.
  • Playstyle:

    • - Neutral/Pacifist: Run away or use Flirt, then spare. Befriending requires giving her water after she collapses.
    - Genocide (Undyne the Undying): Extremely hard. Attacks are relentless. Use highest defense gear (Heart Locket + Cowboy Hat or better). Dodge spears and shoots during yellow SOUL attacks.
  • Unlock Conditions: First chase in Waterfall. Boss fight at the exit of Waterfall (or in Genocide, she appears later).

  • Team Synergy: If befriended, she gives you cooking lessons, and appears in the Asriel fight. She also helps you prepare for the final battle by encouraging you.


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    7. Alphys


  • Background: Royal Scientist. Lizard monster. Insecure and socially awkward.

  • Role: Guide through Hotland (via phone calls), side character, later love interest to Undyne.

  • Strengths:

    • - Technological inventions (Mettaton, the elevator, etc.).
    - Provides information about the Core.
  • Weaknesses:

    • - Cannot fight; she never becomes a boss.
    - Guilt over amalgamates.
  • Playstyle (Not a fighter):

    • - You do not battle Alphys. She assists via phone.
    - In True Pacifist, you navigate the True Lab with her help.
  • Unlock Conditions: Meet at her lab in Hotland.

  • Team Synergy: In the True Pacifist ending, she helps with the final plan and appears at the barrier. Also sends you to the True Lab.


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    8. Mettaton


  • Background: Robot built by Alphys. Originally a ghost possessing the robot body. Now an entertainer.

  • Role: Optional boss in various forms, ratings star.

  • Strengths (As Boss):

    • - Mettaton EX: High HP, powerful attacks (bomb, disco lasers, heart waves). Can be ended by rating his performance.
    - Mettaton NEO in Genocide: Very easy – one hit kill. But if you spare him, he survives.
  • Weaknesses:

    • - Needs an audience; he stops if you ruin his show.
    - Vulnerable to being flattered or ignored.
  • Playstyle:

    • - Neutral/Pacifist: Use ACT to raise or lower his rating. To defeat Mettaton EX, raise rating to 10,000 (use poses, etc.) to make him short-circuit. Or fight normally to lower his HP.
    - Genocide: Mettaton NEO is pathetic – attack once.
  • Unlock Conditions: Appears throughout Hotland. Final battle in the Core (Mettaton EX).

  • Team Synergy: If beaten via ratings, he becomes your friend and appears in the ending. He also helps during the Asriel fight.


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    9. Asgore


  • Background: King of all monsters. Husband of Toriel. Father of Asriel. Wants to break the barrier by absorbing human SOULs.

  • Role: Final boss of Neutral and Pacifist routes (though in True Pacifist, you spare him).

  • Strengths (As Boss):

    • - Trident – attacks that come from all sides.
    - Fire magic – rain of fire.
    - High HP (3500 in Neutral, lower in Pacifist if you befriend everyone).
    - Damage increases as HP drops (desperate attacks).
  • Weaknesses:

    • - Emotionally vulnerable – if you talk to him, he hesitates.
    - In True Pacifist, you don't fight; you spare him after talking.
  • Playstyle:

    • - Neutral: Fight using best weapons, heal frequently. Dodge trident swings and fire columns.
    - Pacifist: Use ACT > Talk multiple times until he gives up. Then spare.
  • Unlock Conditions: Enter New Home. Boss fight after the long hallway.

  • Recommended Equipment: Heart Locket (from his throne room) + Real Knife (if from Genocide) or Empty Gun. Alternatively, The Locket + Worn Dagger for balanced defense.

  • Team Synergy: None directly during fight, but in True Pacifist, everyone helps you convince him.


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    10. Asriel Dreemurr


  • Background: Asgore and Toriel's adopted son. Died and became Flowey. In True Pacifist, he regains his form.

  • Role: Final boss of True Pacifist route.

  • Strengths (As Boss):

    • - God of Hyperdeath: Attacks include stars, bombs, projectiles from every direction.
    - Save and Load powers: He can reset the fight.
    - Immense HP: 9999 in first phase, then different forms.
  • Weaknesses:

    • - Memories of his family – if you show kindness, his attacks weaken.
    - Can be spared by refusing to fight and using MERCY repeatedly.
  • Playstyle:

    • - True Pacifist: Do NOT attack. Use ACT > Save repeatedly. Your friends' SOULs will appear and help. Dodge his attacks (some require precise movement). Eventually he calms down and you spare him.
  • Unlock Conditions: Complete True Pacifist route (befriend all major characters, go to True Lab, then face Asgore and spare him).

  • Recommended Equipment: Not relevant – you never fight. But for survival, wear best armor (Heart Locket + Cowboy Hat or The Locket).

  • Team Synergy: He is the core of the final battle – all your friends (Toriel, Sans, Papyrus, Undyne, Alphys, Mettaton, and even minor characters) send their SOULs to help you. This is the ultimate team synergy moment.


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    11. Other Notable Characters



    #### Napstablook
  • Background: A ghost musician in the Ruins.

  • Role: Optional friendly enemy. Can be spared easily (just compliment). Gives you the Faded Ribbon if you check? Actually they drop items.

  • Strengths/Weaknesses: Minimal. They are a ghost and cannot harm you much.

  • Playstyle: Spare by using ACT > Cheer or Dance.


    • #### Muffet
  • Background: Spider bake sale owner. Lives in Hotland.

  • Role: Optional boss if you don't buy from her (or if you do, she spares you).

  • Strengths (As Boss):

    • - Spider webs and spiders that attack in patterns.
    - Donut poisoning? She uses tea time.
  • Weaknesses:

    • - Can be spared if you donate enough gold to the spider bake sale (or if you have no money).
    - Her attacks are slow and predictable.
  • Unlock Conditions: Meet in Hotland on the bridge. Boss fight if you don't donate or don't wear the Spider Donut.

  • Playstyle: Dodge webs, attack with best weapon. Or use ACT > Donate money.


    • #### Gerson
  • Background: Old turtle historian. Sells items in Waterfall.

  • Role: Shopkeeper, lore exposition.

  • Not a fighter.


    • #### Mad Dummy and Glad Dummy
  • Background: Two dummies in the Ruins and Waterfall.

  • Role: Optional encounter.

  • Playstyle: Fight or spare. Glad Dummy becomes a friend if you cheer.


    • #### Froggit, Whimsun, Moldsmal, etc. (Minor Monsters)
  • Many generic enemies; they have unique spare conditions. This guide focuses on major characters.


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Important Note on Routes and Character Roles



In Undertale, your choices permanently alter which role each character plays. The same character can be a boss, a friend, or a tragic victim depending on your actions. This guide covers their roles in the most common story paths. For a full list of consequences, see the \"Important Notes\" section.

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Conclusion



Every character in Undertale has a distinct role, from the quiet protagonist to the godlike final boss. Understanding their strengths, weaknesses, and unlock conditions is key to navigating the Underground. Remember: team synergy comes not from party mechanics but from the bonds you forge. In the end, it is your mercy and determination that unite them all.

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End of Characters & Roles Guide.