Remus is likely to be shocked and angry. He might immediately want to protect Sirius. He could confront those who are abusing Sirius or try to find a way to get Sirius out of that situation.
Remus would be deeply affected. His reaction would be complex. On one hand, he would feel a great deal of sympathy for Sirius. He would feel guilty for not noticing earlier. He would probably consult his closest friends, like James, to figure out the best way to handle the situation. He would be very cautious about how he approaches Sirius with this discovery, not wanting to make Sirius feel ashamed or embarrassed. He would offer his unwavering support, both physically and mentally, and would do whatever it takes to ensure Sirius is no longer in harm's way.
There could be a plot development where Remus and Sirius go on a journey to find a new place to start over, away from the abuser. Another development could be that Remus uses his intelligence to outwit the abuser legally. The fanfiction could also show how Remus helps Sirius regain his confidence and self - esteem. As Sirius heals, they might start to explore their relationship in a deeper way, whether it's a stronger friendship or something more romantic. There could also be a sub - plot where other characters get involved in different ways, some trying to help and some causing more trouble.
Well, usually Remus would be shocked and heartbroken. He'd try to create a safe space for Harry at Hogwarts. For example, he might let Harry stay in his office when he feels threatened. Remus would also likely try to get Harry some kind of emotional support, like introducing him to some of his more trustworthy friends. He'd be determined to break the cycle of abuse and help Harry grow into a confident and healthy wizard.
She might be horrified and immediately take steps to protect Sirius. For example, she could confront the abuser or report it to the proper authorities within the wizarding world.
Well, James is a loyal friend. So, when he discovers Sirius is abused, he would most probably drop everything else he is doing to focus on Sirius. He'd be angry, not just at the abusers but also at himself for not realizing it sooner. He'd make sure Sirius knew that he wasn't alone and that he had someone who would always be there for him. James might also encourage Sirius to learn self - defense magic more intensively so that he could protect himself in case the abusers tried to harm him again.
Sirius would likely be extremely angry. He already has a protective streak towards Harry. He might immediately confront those he suspects of the abuse, whether it's the Dursleys or others at Hogwarts. He would probably also try to remove Harry from the situation as quickly as possible.
She could be conflicted. On one hand, she might be attracted to both in different ways. Sirius's charm and rebellious nature could draw her, while Remus's intelligence and quiet strength might also appeal to her. So she might struggle with her feelings, trying to figure out which, if either, she truly has deeper feelings for.
Hermione would probably be very angry and start researching ways to help Harry legally in the wizarding world. Ron, on the other hand, would be ready to fight anyone who had hurt Harry.
Often in fanfiction, Hermione might be in a situation where she feels isolated from Harry and Ron. Remus and Sirius, having been through their own share of friendship dramas, step in. Remus could use his calm and gentle demeanor to reassure Hermione that friendships have ups and downs. Sirius, on the other hand, might remind her of how strong she is on her own. They could take her on adventures around the wizarding world, showing her that there are other things to focus on besides the petty squabbles within the group, which would ultimately comfort her.
Sirius might be completely devastated. He could go into a state of shock at first, not believing the news. Then, he might be filled with guilt for not being there for his brother, and anger towards the situation that led to Regulus' death.
Sure. Fanfiction writers love to play with established characters and relationships. In a story where Harry is Remus and Sirius' son, we could see new magical abilities or inheritances coming into play. Maybe he would inherit some of Remus' werewolf - related magic in a different way or Sirius' skills in magic related to his family's heritage. It would also change the emotional dynamics, with a different kind of family support system for Harry.