* He grows up: Dudley undergoes a physical transformation, gaining more weight and height. He also becomes increasingly arrogant and spoiled, often mistreating Harry and his friends.
* He faces a Dementor: At the Quidditch World Cup, Dudley and his friends encounter a horde of Dementors, the soul-sucking creatures guarding the prison of Azkaban. Dudley is frightened and nearly faints, having a glimpse of his own deepest fears.
* He experiences a change: While not a complete personality shift, Dudley shows signs of change following the Dementor encounter. He becomes somewhat more respectful towards Harry and less openly cruel. He also seems to understand that the magical world is real and that Harry is involved in something significant.
Overall, Dudley's role in *Goblet of Fire* is more about highlighting the changes happening in his life and his growing awareness of the magical world. He doesn't have a major plot role, but his small interactions with Harry and the magical events contribute to the overall narrative.