In most cases, their mating is a result of a combination of factors. Maybe it's a deep emotional connection that develops over time, or a dramatic event that makes them realize their feelings for each other. It really depends on how the fanfiction writer decides to shape the story.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, and you're likely to find some great Bella and Howl Pendragon mate fanfictions there.
One popular Bella and Howl Pendragon mate fanfiction might be 'The Bond of Bella and Howl'. It often explores their relationship development in a magical world. It could show how they meet, overcome challenges together, and how their bond as mates strengthens over time.
Well, start with researching the source material if there is any. Know their personalities, quirks, and backstories thoroughly. For a Howl x Sophie fanfic, you could set it in an alternate universe. Say, a world where Howl has lost his magic and Sophie has to help him regain it. This would create a new dynamic in their relationship. You can also focus on their conversations. Howl's flamboyant way of speaking and Sophie's more down - to - earth responses can make for interesting exchanges. And don't forget to add some conflict, like a rival for Sophie's affections or a problem in Howl's past that resurfaces.
One great fanfiction is 'The Once and Future King's Heart'. It beautifully delves into the deep bond between Merlin and Arthur. It shows how their relationship evolves over time, with Merlin's magic playing an important role in protecting Arthur while also creating some interesting conflicts.
One common theme is redemption. Uther has been so against magic, but in these fanfics, he often has to face his prejudices when it comes to Merlin. For example, he might realize that not all magic is evil through Merlin's actions.
One idea could be a time - travel fanfic. Sophie accidentally travels back in time and meets a younger Howl. This gives them a chance to see each other in a different light and also changes the course of their relationship. Another idea is a fanfic where they have to pretend to be married for a mission. They have to deal with all the awkwardness and also the realization that they might actually like the idea of being together. Or, a story where Sophie gets cursed with a powerful spell and Howl has to go on a dangerous quest to find the cure, which deepens their bond.
One common theme could be the conflict between Bobby and Saint Dane. Their opposing natures and goals can create a lot of tension and drama in the fanfic.