Undyne

Undyne is a piscine, anthropomorphic monster. She has blue scales and a long red ponytail. She has red and blue fins on the sides of her head, and a pair of sharp, yellow, protruding teeth. She wears a red eyeshadow and has an eyepatch over her left eye. She also wears a black tank top and blue jeans, but debuts in armor varying in light and dark shades of gray. Her eyes have black vertical pupils and yellow sclera. Undyne has no nose

Undyne is passionate about everything that she does. She acts quickly on her ideas and is steadfast in her beliefs.[3] Though she wants to defeat the protagonist, she also tries to be fair and offers an explanation of how Green Mode works. Asgore taught her the value of pacifism,[4] which is why Undyne sees the protagonist as "a wimpy loser with a big heart." When the protagonist first encounters her, she fights to further Asgore's plan of collecting seven human SOULs but, if the protagonist shows mercy, Undyne just as quickly defends them from Asgore.

She loves to help others and mentors Shyren and Papyrus in various skills. Undyne dislikes puzzles, loves japes,[5] enjoys playing the piano,[6] collecting weaponry, primarily swords,[7] and anime. The latter she shares with her romantic interest, Alphys. Since Alphys told Undyne that anime is actually human history, Undyne regards human history as exciting and cool.[8]

Out of all encountered monsters, Undyne possesses the most Determination. She melts before her death, implying that her body cannot handle the amount of Determination she has.