Their friendship could make the Tri - Wizard Tournament less cutthroat between them. Instead of seeing each other as just competitors, they might help each other out in the tasks. For example, if one of them discovers a useful spell or strategy, they could share it with the other. This would be a big change from the traditional view of the tournament where everyone is out for themselves.
Their friendship could change the perception of dark magic. Tom, having been on the path to becoming Voldemort, might have a different view on dark magic with Harry as his friend. They could work on redefining what is considered dark magic and find ways to use some of those spells in a more positive or controlled way. This could revolutionize the study of magic at Hogwarts and in the wizarding world in general.
For Naruto, Tenten's discipline with her weapon training could inspire him to be more focused in his own training. He might start to practice new techniques with more precision.
Their friendship could also lead to a different perspective on the Uchiha clan's situation. Itachi's actions were complex and his friendship with Naruto could have made Naruto more involved in the Uchiha clan's affairs. This might have led to a different solution to the conflict between the Uchiha clan and Konoha, preventing the massacre. In turn, this would have a huge impact on the political situation in the ninja world.
If Naruto and Madara become friends, it could completely change the power balance. Their combined strength would be a deterrent to any potential invaders. On a more positive note, it could inspire a new generation of ninjas to look beyond past grudges. The younger ninjas would see that even the most bitter enemies can become friends. This could lead to a more unified ninja world where different clans and villages work together more closely. For example, the Uchiha clan might regain more trust within the Leaf village, and other villages might be more open to sharing resources and knowledge.
It deepens their bond. Harry starts to trust Cedric more, seeing him as a reliable friend. This protectiveness makes Harry feel safe around Cedric.
If they were friends before Hogwarts, it could create a lot of internal conflict at Hogwarts. Draco might be torn between his new Slytherin friends who dislike Harry and his long - standing friendship with Harry. He might try to keep their friendship a secret, which could lead to misunderstandings between them.
It can strain their friendship quite a bit. Hermione might start to distance herself from Harry. She could be short - tempered with him, snapping at him for little things that she wouldn't usually care about. For example, if Harry forgets to study for a test like he often does because of his other adventures, Hermione might be more critical than usual and less forgiving, which makes Harry confused and a bit hurt.
Their friendship could change the way Sasuke's character develops. Instead of being so isolated and revenge - focused, with Naruto as a childhood friend, she might be more open to other paths. For example, she could be more willing to stay in the village and help improve it rather than seeking power elsewhere. Naruto, too, would have a different motivation. His drive to bring Sasuke back might be even stronger because of their long - standing friendship, and he would do everything to protect her from the darkness that threatens her.
Their friendship would definitely shake things up. Usually, Gryffindor and Slytherin are at odds. But with Hermione and Pansy being friends, other students might start to question the long - held rivalries. It could lead to more cross - house friendships. For instance, some Gryffindors might be more open to Slytherins and vice versa.
Cedric would probably be very angry.