The next morning, Harry enters the kitchen to see Mr. Weasley taking an urgent message from the Ministry. Mr. Diggory's head is sitting in the fire, talking about someone named Mad-Eye, "please-men," and rogue dustbins. Mr. Diggory says that Mad-Eye is starting his new job today and he has to get off on a minor charge. As Mr. Weasley races away, Mrs. Weasley gives Mr. Diggory a piece of toast and he disappears out of the fire. The Weasley children discuss Mad-Eye Moody; George calls him crazy while Bill points out that he's a friend of Dumbledore's. Charlie tells Harry that Mad-Eye used to be a skilled Auror (a Dark wizard catcher) but now, he's paranoid about everything.
Notice the way that the Weasley children talk about Mad-Eye Moody. George's assessment that Moody is crazy, especially combined with Charlie saying that Moody is paranoid tells Harry that Moody isn't necessarily someone that he should trust. Notably, Charlie is the only one who tries to make sense of why Moody is so paranoid now--being an Auror is likely an emotionally taxing job. This suggests that the other Weasley children haven't yet developed enough empathy to feel for Moody.
Mrs. Weasley hires three Muggle taxis to take her and the children to King's Cross. On platform nine and three-quarters, Charlie cryptically says that he'll be seeing everyone soon, but he and Bill refuse to say anything else except that it's going to be an interesting year. On the train, Hermione, Ron, and Harry hear Malfoy telling someone that his father wanted to send him to Durmstrang, but his mother didn't want him to go so far away. Hermione pulls their door closed and says that Durmstrang has a horrendous reputation for dark magic. She informs Ron that nobody knows where Durmstrang is, as most magical schools, including Hogwarts, are Unplottable and can't be mapped.
When Malfoy mentions Durmstrang without any explanation as to what it is, both Harry and the reader have the opportunity to learn from Hermione that Durmstrang is a school of magic like Hogwarts. This allows the reader to closely follow Harry as he comes of age through learning about the Wizarding world.
Seamus, Dean, and Neville join Harry, Ron, and Hermione to talk about the Quidditch World Cup. Ron shows Neville his figure of Krum but as he starts to tell him about being in the top box, Malfoy appears. Malfoy teases Ron about his dress robes and asks Ron and Harry if they're going to enter. Ron and Harry don't know what Malfoy is talking about, which delights Malfoy. Laughing, he leaves, but Ron is in a bad mood for the rest of the journey.
It's telling that everyone in the compartment is kind to Neville and doesn't treat him differently because he's not a competent wizard. This suggests that the boys in the compartment have the capacity to behave kindly, though Malfoy's teasing of Ron suggests that he doesn't have that capacity yet.