Well, it could be because of jealousy. Maybe Ron gets jealous when Hermione spends a lot of time with another male wizard on a project, and he lashes out at her, starting a fight. Hermione, in turn, is angry at Ron for not trusting her.
In some fanfics, their fight might be triggered by a misunderstanding about their future careers. For example, Hermione might think Ron doesn't support her ambition to further her studies in magic, while Ron may feel Hermione is being too pushy about his own choices.
Hermione could also start the fight. If Ron makes a comment that she perceives as sexist or demeaning to her intelligence, she won't hold back and will start an argument. For example, if Ron says something like 'Girls should focus more on house - work magic than advanced spells' in a joking but wrong - headed way.
A plot could be that the dragon, phoenix, and griffin are being hunted by dark wizards. Hermione, Ron, and Harry decide to protect them. They set up a hidden sanctuary where they use their magic to keep the hunters at bay. Each of them has a special role, like Hermione using her intelligence to create protective spells, Ron handling the more physical aspects of defense, and Harry using his connection to the dark side (from facing Voldemort) to anticipate the hunters' moves.
One possible plot could be Hermione realizing that she and Ron have grown in different directions over the years. Maybe she's focused on her career in magic research and Ron is more into a laid - back life at the Burrow. Their different priorities lead to a rift that eventually results in divorce.
In a fanfic with this theme, perhaps Hermione discovers that Ron has some habits or values that she can't tolerate in the long run. For instance, his lack of punctuality or his laid - back attitude towards certain important matters. She might start to compare her relationship with Ron to what she could have had with someone else, like Viktor Krum. She may regret choosing Ron when she sees how much more in - sync she could have been with someone who shares her passion for knowledge and self - improvement on a more consistent level. It could also be that Ron's family dynamics start to weigh on Hermione more as time passes. The chaos and sometimes backward - thinking in the Weasley family might make her feel out of place and question her choice to marry into it.
One interesting plot could be the challenges they face in adjusting to the new law. For example, they might have to deal with sudden public attention and expectations. Another plot could be how they navigate their relationship while also fulfilling the requirements of the marriage law, like having to attend certain marriage - building events together.
Well, there are fanfictions where Ron and Hermione are tasked with bringing unity among different wizarding communities. Since the war has divided many, they use their influence and friendship to bridge the gaps. It's interesting to see how they handle the politics and different magical traditions. And then there are stories where they explore the non - magical world together post - war. It's a new experience for both of them and the author can play with their reactions to Muggle technology and culture, which is quite fun to read.
One possible plot could be that Ron and Hermione start to focus more on their relationship and their own personal growth, which leads them to unintentionally ignore Harry. They might get caught up in their studies at Hogwarts or in exploring their magical abilities further. For example, Ron could be working hard on becoming a better wizard in the areas he's not so confident in, like spell - casting accuracy. And Hermione might be delving deeper into ancient magic research. This causes Harry to feel a bit left out as he's so used to their trio dynamic.
One possible plot could be how they deal with the reactions of their friends and family. For example, Harry might be shocked at first but then become very supportive. Another plot could involve their studies at Hogwarts. They would have to balance the challenges of pregnancy with their academic responsibilities, like Hermione still trying to ace all her exams while dealing with morning sickness.
There might be a plot where Ron is pitted against other gamers in a high - stakes tournament. He has to overcome his rivals' skills and mind games to emerge victorious. He might also form alliances along the way and face betrayal, adding more drama to the story.
One possible plot could be that Ron is under the influence of a dark spell that makes him act aggressively towards Hermione. Severus, being observant, notices this and steps in to protect Hermione. He uses his potions knowledge to create an antidote for the spell on Ron.