They're popular because it's a dark and interesting twist on the original story. People are intrigued by seeing how Harry copes in such a difficult situation.
Another one could be 'Harry's Ordeal with Umbridge'. This fanfic focuses on the details of the abuse, like the unfair punishments and the psychological torture. It then shows Harry finding strength within himself and from his friends to fight back against Umbridge's tyranny.
One possible consequence could be that she gets fired from her position. If Harry manages to expose her actions, the wizarding school or the Ministry of Magic might not tolerate such blatant abuse of power and take disciplinary action against her.
In the context of the original Harry Potter story, it seems quite abnormal as Umbridge is a very unlikable character to Harry. But in the world of fanfic, anything can happen. Fanfic allows for different interpretations and character developments, so while it's not normal in the traditional sense, it's possible within the creative space of fan - created stories.
Another way Harry could respond is with a sense of shock and disbelief at first. Given that Umbridge is supposed to be in a position of authority, Harry might be momentarily stunned that she would go to such lengths. However, his Gryffindor courage would soon kick in, and he would likely start to resist, perhaps by using his magic in creative ways to protect himself or to disarm Umbridge, all while trying to uphold the values of the wizarding world that oppose such cruel and unjust treatment.
Well, if we consider the 'umbridge finds out harry was abused fanfiction', it really depends on the writer's take. One possibility is that Umbridge, being the power - hungry character she is, might try to cover it up to maintain the status quo at Hogwarts. On the other hand, she could also see it as a way to discredit Dumbledore, thinking he failed to protect Harry. There's also a chance that the discovery could lead to a change in Umbridge's relationship with Harry, from being a tormentor to an unexpected ally, though this would be a huge shift in her personality.
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.
Perhaps in the fanfic, Harry teams up with the other students to stage a large - scale protest against Umbridge. Their united front and the chaos it causes might lead to the school board or the Ministry of Magic realizing that she is not fit to be in charge at Hogwarts. Or Harry could use his connections, like his friendship with Sirius or the Order of the Phoenix members. They could dig up some dirt on Umbridge from her past that makes it impossible for her to continue teaching at Hogwarts.
In 'umbridge abuses harry fanfic', often Umbridge is portrayed as a tyrant. She might verbally abuse Harry, constantly doubting him and his claims about the Dark Lord. For example, she could publicly humiliate him in front of other students, and try to isolate him. This all builds on the canon idea of her as a very unpleasant and unjust character towards Harry in the original story.
There might be some fanfics with this concept that are written in a non - inappropriate way. However, in the official 'Harry Potter' universe, such a situation of Umbridge spanking Harry is not part of the canon. Some fanfic authors might explore this in a more comical or alternative - universe - type of scenario that doesn't involve any adult or inappropriate content. For example, they could write it as a form of extreme disciplinary action in a very different Hogwarts where the rules are warped, but still keep it suitable for a general audience.