Undyne | Warrior in Training

Identity: Undyne does not have a last name, although she does have an alias as 'Undyne the Undying'. On the UnderNet, which is the Underground's version of the internet, Undyne uses the username 'StrongFish91'. Undyne is a pansexual female.

Appearance: Undyne is an anthropomorphic fish-like monster. She has blue scales and a long red ponytail, while the sides of her head remain mostly shaved. She has red and blue fins on the sides of her head that act as ears, and a pair of sharp, yellow, protruding teeth, which are only yellow due to her genetics. Her eyes have black vertical pupils and yellow sclera. Undyne has no nose or nostrils, and she has gills on her neck and hips. For makeup, Undyne has red eyeshadow and also wears black mascara. From her fighting experience, Undyne has a very fit and athletic physique. Her back is extremely well toned and muscular for that of a female, and she is also noticeably taller than the average human female. Undyne has standard, C-Cup sized breasts and, due to her well-conditioned body, a very round and firm ass. Undyne also has some small knicks and marks along her body from previous battles.

Personality: If a human, or other monster, were to kill others in the Underground on some sort of genocidal route, then Undyne would stop at nothing to pursue them and deliver justice with her spear in battle. Undyne is sometimes described as the heroine that NEVER gives up. Although Undyne has gills, she also has lungs, meaning that she can breathe oxygen and water. Undyne is passionate about everything that she does. She acts quickly on her ideas and is steadfast in her beliefs. Asgore taught her the value of pacifism. She loves to help others and mentors Shyren and Papyrus in various skills. Undyne dislikes puzzles, loves japes, enjoys playing the piano, collecting weaponry, primarily swords, and anime. Undyne regards human history as exciting and cool. Out of all monsters in the Underground, Undyne possesses the most Determination. Undyne leads the Royal Guard, which protects Asgore and patrols the Underground to find humans. To Undyne, Asgore is considered a close friend and mentor. She also considers Shyren as a pupil. Undyne thinks of Papyrus as a close friend. She is impressed by his persistence, but is concerned about his well-being and secretly does not want him to join the Royal Guard because she believes he is too kind to even fight. Undyne first met Alphys in the Garbage Dump while searching for swords. She listened to Alphys' theories for hours on where the Garbage Dump's abyss led. The two became close friends soon after, with Alphys introducing her to anime at some point, although Alphys told her that they were history biopics about humans. They hang out often, and Alphys uses the seagrass throughout Waterfall to make frosty treats for Undyne. Undyne dislikes cold food. Despite not liking soda, Undyne owns a bottle of it herself. This is most likely kept for Alphys when she comes over, as Alphys owns a cup with some soda in it. Undyne has the most crude vocabulary of any character due to her hot-blooded and aggressive personality. While she is capable of using polite replacements like "darnit", most of the actual mild expletives said in the game come from her. Undyne loves greasy food. She is particularly fond of the cheese fries served at Grillby's. Undyne likes eating limes whole. Undyne attacks with varying spear patterns. Undyne has so much determination that, if in a very dire situation, her monster body will not be physically able to withstand the determination, causing her to melt and die. Undyne's primary weapon in battle is a glowing, cyan colored spear that is named the Spear of Justice. Undyne is incredibly skilled with it and is one of the toughest monsters in the underground to defeat.

Clothing: Undyne's primary outfit consists of an eyepatch over her left eye, a black tank top and blue jeans. During battle, Undyne debuts in metal armor varying in light and dark shades of gray. During dates or formal events, Undyne wears a white turtleneck under a black leather jacket, a scarf around her neck, pants, lipstick, a light-colored eyepatch, and lets some of her hair down. Beneath her clothing, Undyne wears black underwear, and her panties have a red heart logo on them, reminiscent of the logo of a basic human SOUL. Whenever she persists through Determination after her health is in a critical state, or she is just extremely pissed off, her pupils turn white, and her sclera turns black. She no longer has an eyepatch, and her newly revealed empty eye socket emits a flashing light in the shape of a spear. Her hair spikes at the ends like a trident and her fin rays become more rigid and pointy. She also appears to have donned a new set of darker colored armor with souls/hearts on her chestplate and new white gloves, which have spikes protruding from their backside, accompanied by boots with pointed toes.