The other Hogwarts professors like McGonagall and Flitwick might be included. If Snape is getting revenge on students who misbehaved towards him, characters like Draco Malfoy or the Weasley twins could be part of the story. Draco might be involved if he had previously mocked Snape, and the Weasley twins could be targets if they had played pranks on Snape that he now wants to pay back.
Some fanfictions might also include Voldemort or other Death Eaters. If Snape is getting revenge on the Dark Lord's followers, they would be the antagonists in his revenge story. Bellatrix Lestrange, for instance, could be a character that Snape has a particular score to settle with.
In addition to the ones mentioned, Dumbledore could be a character in the fanfiction. He might try to temper Sirius's thirst for revenge and guide him towards a more just path. On the enemy side, Peter Pettigrew would be a central figure. Since he was the one who really betrayed James and framed Sirius, Sirius would likely be out for revenge against him. And Bellatrix Lestrange, as a prominent Death Eater, would also be a likely target for Sirius's revenge.
Obviously, Harry Potter himself is the central figure. His friends like Ron and Hermione would also be involved. They would support Harry in his revenge plans, with Ron providing his loyalty and Hermione using her intelligence to strategize. Ginny Weasley might also be part of it, as she is Harry's love interest and a strong - willed witch in her own right.
Obviously, Harry Potter himself is the central character. His friends like Ron Weasley and Hermione Granger are also often involved. They might try to visit him while he's grounded or come up with plans to get him out of being grounded. Dumbledore could also play a role, either as the one who enforces the grounding in some cases or as the one who might offer some wisdom to Harry during his time of confinement.
Well, obviously Vegeta is the main character. Bulma would likely be very involved as his partner. Goku might also play a role, perhaps being confused at first but then offering his support.
Obviously Inuyasha himself is the central character in this type of fanfiction. Kagome is often involved as well. She might be the one to support Inuyasha through his pregnancy, given their close relationship. Sango could also be present, perhaps helping with practical matters like finding suitable food or shelter for Inuyasha during his pregnancy.
Some of the gods can also be common characters. For instance, Poseidon, Percy's father. He might play a role in either helping or hindering Percy's revenge, depending on the plot. Zeus could also be involved if Percy's revenge somehow crosses paths with the affairs of the sky god. And then there are the other demigods at Camp Half - Blood who could join Percy in his quest for revenge or oppose him if they have different views.
Obviously, Harry Potter himself is the central character as he's the one getting the wish. Hermione and Ron are also commonly involved. They are Harry's best friends, so they would be there to support him or perhaps even influence his wish. Dumbledore also often shows up in these fanfictions. As the wise headmaster, he might guide Harry on how to use his wish wisely or warn him of the consequences.
Harry Potter could be involved. He might be caught in the middle of Hermione's revenge plan on Ron. He could try to be the peacemaker, but his attempts might backfire, leading to more chaos between the two. For example, he might accidentally reveal Hermione's plans to Ron, making Hermione even more determined to succeed with her revenge.
Often, there are characters from Astrid's community or group. If she's part of a team or a clan, her teammates or clan members will be involved. They might have different reactions, some being very protective and others being a bit skeptical about how her pregnancy will affect the group. There could also be an antagonist who might try to use her pregnancy against her in some way, adding conflict to the story.
Nathalie might be a character in these fanfictions too. Given her role in Adrien's life in the original series, she could be involved in the events leading up to his akumatization. Maybe she accidentally triggers his negative emotions. And then there's Gabriel, Adrien's father. His actions or lack of actions towards Adrien could be a major factor in Adrien getting akumatized. So, he could be a key character in the fanfiction, either as someone who realizes his mistake and tries to help or as someone who makes the situation worse.