They could face expulsion from the wizarding community if the abuse is severe enough. The wizarding world has its own laws and rules, and abusing a young wizard like Harry would be a serious offense.
They might be shocked and immediately try to offer protection. For example, they could take Harry to a safe place within the wizarding world where he can't be reached by his abusers.
Well, it really depends on the specific characteristics of the champion in this fanfiction. If the champion is a very impulsive and kind - hearted person, they might confront the abuser right away. But if they are more calculating, they could gather evidence first. They would also probably feel a sense of responsibility to help Harry, given that they now know about his situation. They might offer Harry a place to stay, or try to get the proper authorities involved in the wizarding world to deal with the abuser.
You might want to check out 'Secrets Unveiled'. In this story, Draco discovers Harry's abuse by accident when he follows him to an abandoned part of the school.
After the discovery, a possible plot development could be that the champion takes Harry away to a secret location to keep him safe. From there, they might try to heal Harry's emotional wounds. As they do this, they could encounter various obstacles, like the abuser trying to find them or the wizarding authorities not believing their story. The champion might then have to prove Harry's situation, which could involve finding witnesses or evidence. Another development could be that the champion's actions draw the attention of a powerful and mysterious figure in the wizarding world, who either helps or hinders their efforts to protect Harry. This could lead to a whole new set of challenges and adventures in the fanfiction.
They would likely be shocked and angry. The Weasleys are a kind - hearted family. They might immediately take Harry under their wing more protectively, like Molly Weasley would probably start fussing over him even more, making sure he has enough to eat and a warm place to sleep.
Well, the goblins could start a revolution of sorts. If they find out Harry is abused, they might see it as a sign of the general corruption and unfairness in the wizarding world towards those without power. They could use Harry as a symbol of this oppression and start demanding changes in the way the wizarding world treats its children. This would likely lead to a lot of conflict with the wizarding authorities, but it could also bring about much - needed reforms.
In some fanfictions, the Death Eaters might see Harry as a tool. If they find out he's abused, they could try to manipulate him. They might think that with his power and now his vulnerability, they can turn him to their side, using his anger at his abusers as a driving force.
The Weasleys are likely to be horrified. They are a warm - hearted family. Mrs. Weasley might immediately take on a motherly role towards Harry, perhaps making him his favorite foods and fussing over him. Mr. Weasley could become very protective, ensuring that Harry is safe from any further harm. The siblings, like Ron, might be angry that Harry had to endure such abuse and vow to always have his back.