The semi-immortal monk Ling was involved in the turbulence of time and space while exploring a small secret realm that was about to collapse. His power was unstable and he turned into an 11-year-old child. He was picked up by Hagrid near the Forbidden Forest, and then received a letter of admission to Hogwarts and entered Hogwarts to study.
Purpose: The child has no food to eat, so he cuts his own legs to survive