Mary Sue Undyne lives in the AU Suetale and is the strongest, bravest, fastest, coolest, and most loved monster in the Underground. And possibly in the Multiverse.


She has blue skin and red eyeshadow, like the original Undyne. However, her wrists and ankles have been cut. Her hair is a brighter red with blonde highlights. Her gills are all sorts of colors that I refuse to go over. Her eyes are now black and gray instead of black and yellow (please do not meme-spam me in the comments). Her tank top is yellow with fuzzy purple dots on it, and her pants are black and white. Her boots are orange with red and gray-blue stripes. She has rainbow horns that she got from Alphys when she was tested on once. Her eyepatch is just an eyepatch, but the image on it has her SOUL on it (yes, it is dripping with Determination).


About the same as the original Undyne's in fighting spirit, but she is kinder to Papyrus and rougher to Alphys. She has a crush on Alphys and has always been a homosexual. She is suicidal, but covers it up well. Because of the Stu Virus, she is an egotistical, narcissistic brat that cares mostly, if not only, for herself. She will randomly break out in song.

Abilities and Weaknesses


Everything, but now he has her horns, too! Despite being able to use everything, she uses spears and swords as her main weapons, mostly swords. She can use Karmic Retribution, but chooses not to. She doesn't use any SOUL mode except for Green Mode.

Other stuff

Teleportation, mind control...this fish lives up to her name!


Nothing, except that she has a strong allergy to strawberries.


Barely Sue Alphys: She has had a crush on Alphys for a long time, and before that, they were friends.

Frisk/Player: She dislikes Frisk at first (Frisk has the ninth soul that Asgore needed to break the barrier), but after a hangout, the two quickly bond.

Gary Stu Papyrus: She teaches Papyrus about cooking, but she also lets him take breaks if he gets too overwhelmed, or if his joints fall off (this has happened three times before).

Gary Stu Sans: She is Sans' boss. She takes a great disliking to him because he's always off, boasting about how great he is, and he never actually works.

Gary Stu Asgore: The two grew up together, and Asgore trained her to be the head of the Royal Guard.

Slightly Sue Toriel: Undyne regularly visits Toriel to keep her company. In fact, Undyne was there while Frisk was in the Ruins, she was just sleeping! The "room under renovations" was being turned into a guest room.


  • Undyne was always a homosexual, and once Papyrus asked her out on a date. She told him the truth, and Papyrus never really cared. He was just happy to be in her company.
  • Undyne is 19 in human years. She is 40 in monster years.
  • Undyne thought about quitting the Royal Guard once, but this was when Papyrus came into her life. She focused her life on his cooking lessons and soon, she wanted to stay in the Royal Guard.
  • Undyne never knew Gerson.
  • Undyne, however, did see Gaster in her dreams, and they talked and played card games together. When Papyrus met her, Gaster stopped coming.

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