Undyne was tough, even just born. When her mother looked down on her, she jumped out of her arms, and began, seemingly already learned, crawling rapidly across the floor to the fridge. She looked at her mother imploringly making harsh noises which signaled she wanted to eat. Her mother stared at her, confused. She had never seen any child like this before.
    In a daze, she walked over to the fridge, took out some meat and gave it to the child, who devoured it. Her mother sat on the couch and stared at Undyne. Undyne crawled over to her mother and curled up next to her. Both of them, tired dozed off to sleep together. By the age of three, her mother decided Undyne was too much of a handful and sent her to school.
Undyne became fast friends with the other students. When Gerson, a mighty warrior of the Royal Guard, came to school, Undyne decided to put her enthusiasm to use, and join the Royal Guard. She began shouting at other students to fight her. When shy Alphys and Mettaton walked past her, she shouted, "FIGHT ME!" at them. Mettaton looked at her lazily, stretched out one of his arms, picked her up and placed her at the other side of the playground. Alphys didn't even bat an eye.
Finally, when Undyne couldn't find anyone else to fight her, she decided to go up to the future king himself, Asgore. She rushed up to him screaming, "FIGHT ME!!" Asgore replied, "You don't want that." "Are you scared?" Undyne taunted. "Unlikely." Asgore said. "Then do it." Undyne ordered. "As you wish." Asgore answered. Five minutes later, Undyne was flat on the ground, dazed from his attacks. "I can't believe you." another student, Toriel, said. "But she was LITERALLY asking for it." Asgore whined. "Aaaaaand you listened to her." Toriel reprehended. "...Maybe" Asgore replied guiltily.
After Undyne had recovered fully (but with a large amount of bruises) Asgore came over to her and said, "Sorry about earlier, do you want to know how to beat me?" "Um, sure?" Undyne replied nervously. From then on Undyne and Asgore trained together until Undyne was strong enough to knock Asgore down in battle. Instead of looking angry or hurt, Asgore sat up with a huge proud grin on his face. When he became king, he assigned Undyne to the position of the Royal Guard. Since Undyne's parents had disappeared in Chara's rampage, Asgore became like a second father to Undyne.