Harry sits blankly and tells Ron and Hermione that he didn't put his name in. There's no applause, but Dumbledore calls for Harry to follow the other champions. Harry trips on his robes as he gets up and walks through the doors. Fleur, Krum, and Cedric stand by the fireplace, looking impressive and mature. Fleur addresses Harry as though he's a messenger and moments later, Bagman excitedly enters and introduces Harry as the fourth champion. The other three look bewildered and angry. Bagman, however, smiles and says that Harry's obligated to compete.
Everything that Harry thinks and does after learning that he's the fourth champion makes him seem very different from the other champions: in his immaturity and youth he trips on his robes and recognizes that the others are all young adults, not children. This suggests that going forward, Harry's goal will be to look just as mature and competent as his competitors.
Dumbledore, Mr. Crouch, Madame Maxime, Karkaroff, Snape, and McGonagall interrupt Bagman as they enter the room. Madame Maxime and Karkaroff are furious, while Snape maliciously says that Harry has no respect for rules. Dumbledore silences Snape and asks Harry to confirm that he didn't put his name in the goblet. Both Maxime and Karkaroff accuse Dumbledore of making a mistake with his Age Line. Angrily, McGonagall insists that everyone should believe Harry.
When Dumbledore and McGonagall insist that everyone should believe Harry outright, it shows that both of them believe that their students, though they're children, are deserving of respect and trust just as adults are. This begins to distance Dumbledore from Maxime and Karkaroff, given that they suspect Harry of foul play.
Karkaroff asks Mr. Crouch for his opinion. Curtly, Mr. Crouch says that they must follow the rules; Harry must compete. Karkaroff insists that they set the Goblet of Fire up again until each school has two champions, but Bagman points out that it won't reignite until the next tournament. When Karkaroff threatens to leave, Moody enters and reminds him that the tournament is a binding magical contract and all the champions must compete. Moody insists that someone put Harry's name in, knowing he'd have to compete.
Though Karkaroff's insistence on fairness and equity is admirable, it's telling that he finds Harry threatening at all. At fourteen, Harry is short at least three years of magical education and therefore shouldn't pose much of a threat to Krum's chances of winning. This suggests that Karkaroff and Maxime understand that youth isn't much of a handicap; what will matter is Harry's maturity.
Maxime and Karkaroff insist that whoever put Harry's name in wants to give Hogwarts a better chance at winning, but Moody suggests that whoever did it might want Harry dead. Karkaroff points out that Moody sees assassination plots everywhere. The two argue but Dumbledore stops them and says that Harry still has to compete. Bagman is the only one who looks excited, and he asks Mr. Crouch to give the champions their instructions. Harry thinks that Mr. Crouch looks ill as he says that their first task will test their courage, that the champions cannot accept help, and that they'll be excused from final testing.
While the adults in Harry's life have already established that Moody is somewhat paranoid, it's also important to note that what he's doing is examining all options available to him while not deciding on any one of them. This then offers Harry an example of how to interpret information, come up with a number of ideas, but also keep an open mind so that when more information arises, he can make a better decision.
Dumbledore sends Harry and Cedric to bed. On their way out, Cedric asks how Harry got his name in and seems unconvinced when Harry says he didn't put it in the goblet. Harry wonders if anyone is going to believe him and if he has any chance of surviving. He wonders if whoever put his name in the goblet wants him dead or just wants to make him look like a fool. Harry knows that Voldemort is after him, but can't figure out how Voldemort could've done this. He remembers his earlier dream and shudders.
Wondering if someone wants to make Harry look foolish reveals Harry's youth; as such a young competitor, it's unlikely that any adult aware of what's to come would hold it against a fourteen-year-old for performing poorly in this event. This shows that Harry is still youthfully self-centered and is overly concerned with how others perceive him.
In the common room, the Gryffindors are already celebrating. Nobody seems to care that Harry doesn't want to celebrate and Lee drapes a Gryffindor banner around Harry's shoulders. A half hour later, Harry angrily excuses himself to go to bed and find Ron. Ron is in the dormitory, grinning oddly. Harry rips off the Gryffindor banner as Ron offers congratulations and asks how Harry got across the Age Line. Ron insists that Harry can tell him the truth and won't listen when Harry says he didn't do it. Ron finally pulls his curtains shut around his bed, leaving Harry feeling more alone than ever.
For Ron, Harry getting chosen means that once again, Ron is relegated to the background and forced to accept that he and Harry are extremely different people in terms of fame and privilege. Before Harry's name came out, it seemed as though Harry and Ron were going to be on equal footing for once, given that they were both going to be spectators.