Norbert was first introduced in the first book. He was given to Hagrid by a stranger. Hagrid didn't know that the stranger was really one of Voldemort's servants. The servant worked at Hogwarts, disguised as a teacher. He was Professor Quirrel.

Norbert's egg hatched in Hagrid's hut. Harry and his friends were there. Ron's brother was a dragon tamer. Malfoy saw that Hagrid illegally smuggled a dragon egg. Harry and his friends had no choice but to release Norbert into the wild.