Ron Weasley, most likely the second most important character in the book, is one of Harry’s best friends, along with Hermione Granger. Harry often stays at his house over summer break from Hogwarts and sees the rest of his family, who are all very poor. Ron is very embarrassed by this fact and is often disappointed, as clearly shown at the end of Chapter 10 when Ron has to bring a very old, cheap, and embarrassing dress robe rather than a more expensive one.
When Harry is first picked by the Goblet of Fire to compete in the Triwizard Tournament, Ron believes that Harry put his name in just to gain more attention and be more popular at school, and is angry at him. He is naturally jealous, too, because he never gets any attention at school, and consistently having a best friend who’s one of the most famous wizards in the world was very difficult for him over his years at Hogwarts. So when Ron thought that Harry tried to trick his way into more popularity, it was one step too far for Ron.
However, Ron eventually realized that Harry didn’t volunteer for the tournament after seeing for himself how dangerous the tasks were. From then on, he made sure to support Harry in the tournament and do his best to help him win.
One of the most interesting parts of the story related to Ron is how Ron’s fascination with Victor Krum, a famous Quidditch (a wizarding sport) player, changes from very high to extremely disapproving. At the beginning of the book, when Ron, Harry, and Hermione watch the Quidditch World Cup, Ron keeps telling them how great he thinks Krum is– “He’s unbelievable. He’s really young too. Only just eighteen or something. He’s a genius, you wait until tonight, you’ll see.” However, at the Yule Ball at Hogwarts, he is suddenly infuriated with him because he went with Hermione, whom Ron likely realized that he wanted to go with but didn’t realize until it was too late. To him, it feels like nothing ever goes his way– his family is very poor, he never gets as much attention as Harry, and he isn’t able to go with Hermione to the ball.