A powerful and ancient magical being might force Harry to marry. This being could have its own motives that are not immediately clear. It could be related to some prophecy or an old magical law that only this being knows about. Harry would then have to figure out the nature of this being and how to persuade it to release him from the forced marriage.
One possible plot could be that there is a powerful dark wizard who forces Harry into marriage as part of a grand scheme to gain control over the wizarding world. Maybe this wizard has some ancient magic that compels Harry and he has to find a way to break free while also dealing with the political and social ramifications of this forced union within the wizarding community.
One reason could be for the sake of exploring different relationship dynamics. Fans want to see how Harry would react in a situation that is completely out of his control, like a forced marriage. It adds a new layer of drama to his character.
One possible plotline could be Harry initially resisting the marriage due to feeling forced into it, but as he spends more time with Ginny, he discovers new sides of her and gradually falls in love. For example, they might have to work together to face some new dark magic threat in the wizarding world, and through that shared experience, their relationship deepens.
At first, their relationship might become strained. Harry, being forced into the marriage, could be cold and distant towards Ginny. However, as time passes, they might start to understand each other's situations better. For example, they could share their fears and frustrations about the forced union, which could gradually bring them closer.
One reason could be some sort of ancient magical law or prophecy. Maybe there's a hidden clause that says for the greater good of the wizarding world, they need to be married. It could be related to some power or protection that their union might bring.
There are indeed such fanfictions. Some explore really interesting concepts within this odd scenario. For example, in some stories, the forced marriage is a part of a dark plot by Voldemort to gain more power over the wizarding world through Harry. Others might focus on how Harry copes with this situation and tries to find a way out while also dealing with his complex feelings towards Voldemort. It's a very unique concept that can lead to some very creative storytelling.
One popular 'Harry forced to marry' fanfiction might be 'Forced Bond' where the author creates an interesting plot around the forced marriage concept. It delves into how Harry copes with the situation and the relationships that develop as a result.
Yes, there are some fanfictions with this rather strange premise. You can often find them on various fanfiction websites like Archive of Our Own (AO3). Just search for the relevant tags.
The relationship might also develop in a more magical way. There could be some sort of magical bond that was created when they were forced to marry. This bond makes them more in tune with each other's emotions. As they learn to understand and control this bond, their relationship blossoms. They start to have feelings for each other that are deeper than just friendship, and eventually, they might truly fall in love.