The main characters could be a couple of first - year students at Hogwarts. They are curious and eager to learn about potions, especially amortentia. Their names could be Lily and James, not related to the famous Potter parents but just coincidence.
Maybe in the 'amortentia for kids hp fanfic', a young wizard discovers a recipe for a modified amortentia that instead of causing romantic love, creates strong bonds of friendship. He then uses it on his shy friends to help them become more confident and make new friends at Hogwarts. This could lead to a series of adventures as they explore the new relationships formed.
It could be Harry Potter himself as he often has to face powerful and symbolic foes. He might be the one to interact with the dragon, the lion and the serpent in some way.
It might feature a new character who is an expert in martial arts, like a transfer student from an Asian wizarding school, and they could be a main character along with Harry and his friends. They could bring in new ways of fighting dark magic using their martial arts skills.
I don't know for sure as I haven't read it. But it could be the children of the main characters from Sword Art Online's Aincrad arc and some well - known characters from the Harry Potter series.
It could be Harry, Ron and Hermione. They are the central characters in the Harry Potter series and are likely to be involved in such a fan - created scenario like a poker game.
It's hard to say without actually reading it. But it could be the usual suspects like Harry, Hermione, and Ron, as they often find themselves in situations full of contradictions in the original series.
There could also be some of the teachers or staff from Hogwarts in the 'breeding grounds hp fanfic'. For example, Hagrid would be a very likely character to be involved, given his love and knowledge of magical creatures. His presence could add a sense of authenticity and guidance in the breeding ground scenarios.
Harry Potter himself could be the main character. Imagine in the final battle against Voldemort, Harry uses a new and extremely powerful magic that he doesn't fully understand. He defeats Voldemort, but in the process, it causes some sort of permanent damage to his own magic or the magic of Hogwarts. It's a victory, but at a cost, which fits the concept of a Cadmean victory.
Another option is to have Hinata and Numbuh Three as the main characters. Hinata's shyness and her growth in Naruto could be paralleled with Numbuh Three's own journey of self - discovery in the KND. They could support each other and show different aspects of courage in the face of challenges.
Typically, the main characters in 'hp next gen fanfic' are the children of the original series' main characters. For example, James Sirius Potter, Albus Severus Potter, and Lily Luna Potter, who are Harry and Ginny's children. There are also characters like Scorpius Malfoy, Draco's son.