An old - fashioned Hogwarts professor who doesn't approve of Creevey's hobby of photography. This professor believes that it's a distraction from studies and might confiscate Creevey's camera. Harry stands up for Creevey, leading to a conflict between the students and the professor. In the end, they might find a way to convince the professor that photography can also be a form of magical art and documentation, but not before there are some tense moments between them.
It could be a jealous student. Maybe there's a Gryffindor who is envious of Creevey's friendship with Harry. This student might spread rumors about Creevey, saying that he's only using Harry for his fame. This causes some tension between Harry and Creevey at first, but they eventually figure out the truth and strengthen their bond in the face of this false accusation.
In this fanfiction, it could be that Creevey is being bullied by some Slytherin students. Harry, being his friend, steps in to protect him. Harry then decides to teach Creevey some basic self - defense spells. As they practice together, they not only grow closer as friends but also Creevey gains more confidence. This newfound confidence leads Creevey to stand up for other students who are being bullied, and he and Harry become a symbol of friendship and standing up for what's right at Hogwarts.
It could be Draco Malfoy. Since Harry and Ron are not friends, Draco could take advantage of their weakened state. He might try to turn them against each other even more, perhaps by spreading false information about one to the other. He could also try to isolate Harry from the Gryffindor group since Ron is no longer on his side, making Harry an easier target for his bullying.
The Ministry of Magic could also be the main antagonist in this case. If the Ministry is corrupted or under the influence of dark forces, they could manipulate Harry's friends. They might convince his friends that Harry is a danger to the wizarding world order, and his friends, being naive or misinformed, end up betraying him.
Well, one possible plot could be that Harry finally gets to experience a warm and loving family environment. The Creevey family might help him heal from all the traumas he faced at the Dursleys. They could encourage his magical abilities in a different way compared to Hogwarts, perhaps with more home - based magical experiments.
It could be a rogue ninja who has a vendetta against cats for some strange reason. This ninja might try to capture Tora to use it as bait for Naruto or just because he wants to harm it. So, he becomes the main obstacle in Naruto and Tora's friendship.
It could be Hades. He might not like the idea of Percy, a son of Poseidon, being friends with Apollo. Hades could see it as a threat to his own power or plans in the underworld.
There could be a power - hungry shinobi within Konoha itself. He is jealous of the bond between Naruto and Shikamaru and how they are getting stronger together. So, he tries to set them up, making it seem like they are betraying the village. He wants to break their friendship and take their place as a respected ninja in the village.
A power - hungry merman who wants to rule over all the mer - people. He sees Harry as a threat because Harry has some special powers or a claim to the throne that he doesn't want to share.
There could also be a powerful, corrupt magical creature as the antagonist. This creature might have some grudge against humans in general or specifically against Harry and Ginny because of their past actions. It could use its magic to make them disappear and keep them trapped in its domain.
It could be a rogue wizard who has also acquired Muggle weapons and is using them to cause chaos. This wizard might be jealous of Harry's fame and wants to use the gun to prove that he's more powerful.