In some fanfictions, it could be a more emotional moment. Sirius has a deep connection with Harry, and perhaps he pins Harry down in a moment of intense fear or worry. Like if Harry was about to sacrifice himself for something, and Sirius couldn't bear the thought of losing him, so he physically restrains him.
It might also be a situation where Sirius is frustrated with Harry for doing something reckless. He pins Harry down to get him to listen and understand the seriousness of his actions. For example, if Harry was planning to go after a powerful enemy alone without a proper plan.
It could strengthen their relationship. If Sirius is pinning Harry down to protect him, Harry might come to realize how much Sirius cares for his safety and well - being. This act of protection can deepen their bond of trust.
One possible scenario could be that Sirius Black spanks Harry as a form of discipline for some dangerous or disobedient behavior that Harry has engaged in within the context of the fanfiction's plot.
Perhaps in the fanfiction, Sirius gets involved with the wrong crowd. And Harry, who has a strong sense of right and wrong, can't stand being associated with Sirius any longer. Or maybe Sirius has a falling out with one of Harry's other important people, like Hermione or Ron, and Harry takes their side and starts to hate Sirius as a result.
One possible reason could be a misunderstanding. Maybe some false information was spread about Harry that made Sirius believe he had done something unforgivable. For example, if there were rumors that Harry was involved with dark magic in some way, Sirius, who has a strong aversion to the dark side, might be quick to disown him.
A plotline might involve Sirius and Harry living together and Sirius trying to give Harry a normal family life. He could cook for Harry, help him with his homework, and they could have a pet together. Maybe they get a Kneazle, and Harry learns to take care of it with Sirius' guidance. This would be a contrast to the cold and often neglectful treatment he received from the Dursleys. And as Harry grows, Sirius could introduce him to his old friends like Remus Lupin in a more family - like setting, strengthening Harry's support system.
One interesting scenario could be in a Quidditch match gone wrong. Maybe Draco, in a fit of over - competitiveness, pins Harry against the side of the stadium during a mid - air scuffle. It could be a moment of intense rivalry and unexpected physical contact that changes their dynamic.
Well, depending on the context of the fanfiction, Sirius could also be very understanding. If he knew that Harry and Hermione were just having a private conversation about important matters like their fight against Voldemort or schoolwork, he might just give them a knowing smile and say something like 'Carry on, then. Just making sure everything's all right.' He's a rather perceptive character, after all. And he trusts Harry a great deal, so he would likely give them the benefit of the doubt before assuming anything untoward.
One possible plotline could be that Sirius Black has been under some dark magic influence. Maybe a powerful dark wizard has managed to manipulate his mind, making him believe Harry Potter is a threat to him or the wizarding world in some false way. This could lead to a series of events where Harry tries to prove his innocence and figure out what's wrong with Sirius. Another could be that there's a misunderstanding based on some prophecy or false information spread within the wizarding community. Sirius, being impulsive, jumps to conclusions and decides to disown Harry without fully understanding the situation.
One possible plotline could be that Sirius and Remus initially struggle with their inappropriate feelings towards Harry. They might then realize it's wrong and instead focus on their roles as his protectors. They could channel their strong emotions into teaching Harry more about his parents and the wizarding world, turning a potentially dark concept into a positive mentoring relationship.
Well, one possibility could be Itachi as a wizard in the Harry Potter world. Maybe he'd be in Slytherin due to his cunning nature. He could use his Sharingan abilities in a magical way, like seeing through invisibility cloaks or detecting hidden spells.