First of all, Arthur would offer his own home as a safe haven for Harry. He would then try to find out the root cause of the abuse. If it's a person, he would try to deal with that person legally or through some other proper means. He would also introduce Harry to positive and helpful people in the fanfiction world. These people could help Harry heal and grow. Arthur would be by Harry's side all the time, reassuring him that he is not alone and that things will get better.
He may report the abuse to the relevant authorities in the fanfiction setting.
Cedric might first talk to Harry privately to get all the details. Then he could go to Dumbledore for help.
Arthur might be shocked and immediately want to protect Harry. He could start by confronting those who are abusing Harry or find a safe place for Harry to stay.
He could start teaching Harry some defensive magic in case the abuser tries to come back. Also, Bill might use his connections to find a healer or a counselor who can help Harry deal with the emotional trauma of the abuse.
Amelia Bones might confront the abusers directly. If it's the Dursleys, she would give them a stern warning or even use magic to make sure they can't harm Harry anymore. She could also arrange for Harry to have proper magical education away from the negative environment he was in, so he can grow and develop his skills without fear.
Thalia could take multiple steps. She would be a constant source of emotional support for Percy. She might arrange for him to see someone who can help him deal with the trauma, like a healer or a wise old character in their world. Also, she would work on rebuilding Percy's self - esteem. She could do this by highlighting his strengths and achievements. For example, she might remind him of all the times he was brave in battles, which would help him see that the abuse doesn't define him.
Rita could have a complex reaction. On one hand, she might feel a twinge of pity for Harry, but on the other, her journalist instincts would kick in. She might start interviewing people around Harry surreptitiously to gather more information. However, she would also be careful not to cross certain lines as she doesn't want to make powerful enemies in the wizarding community. She might try to get Harry's side of the story, but in a way that serves her own purposes, like getting exclusive rights to his story so she can write a best - selling exposé.
His life changes significantly. Firstly, he no longer has to hide the abuse. He can be more open about his feelings and experiences. This could lead to him getting the help he needs, like emotional support from his friends.
The plot development in the 'umbridge finds out harry was abused fanfiction' can be quite complex. At first, Umbridge may be in denial, not wanting to believe that such a thing could happen to Harry. As she digs deeper and realizes it's true, she could be faced with a moral dilemma. She might be tempted to continue her oppressive ways, but the knowledge of Harry's abuse could also nudge her towards redemption. This could involve her making amends with Harry, or even joining forces with him against the real threats in the wizarding world. However, her pride and self - interest would constantly be at odds with any positive changes, making for a very tense and interesting plot.
In the fanfiction, if Ron finds out Harry is abused, it's a complex situation. Ron's reaction would be multi - faceted. Emotionally, he'd be a mess. He loves Harry like a brother. He might feel guilty for not noticing earlier. Ron would also start to view Harry in a new light, with more compassion and understanding. He would use his Weasley family connections to find resources or help for Harry. Maybe he'd ask his mother for advice or even get his older brothers involved if the abuse was from a powerful source within the wizarding world.
He might be shocked at first. Then he could feel a strong sense of protectiveness towards Harry. Maybe he immediately tries to find ways to keep Harry safe from further harm, like staying closer to him at all times.