Growth and self - discovery are other themes. The relationship between the two can be a catalyst for each character to learn more about themselves, as they interact and face different situations together in the fanfic stories.
Another theme could be family acceptance. Their families' reactions to their marriage and how they deal with any potential issues or misunderstandings related to family expectations.
One great place to start looking for Sachiko x Yumi fanfic is on fanfiction.net. There are often many different takes on their relationship in the fanfics there.
One common theme could be friendship. Paris and Yumi might be depicted as having a really strong bond in the fanfics. Another theme could be discovery, like they are discovering new things about each other or about a new place together.
One great place to start looking for Sachiko and Yumi married fanfiction is Archive of Our Own (AO3). It has a large collection of fan works. You can search for the relevant tags like 'Sachiko and Yumi' and'marriage' to find some interesting stories.
To find great 'yumi and sachiko' rated M fanfiction, start by exploring different fanfiction communities dedicated to their source material. Since it's rated M, it might contain more mature themes like deeper emotional exploration or more complex character interactions. You can also ask in relevant forums or groups if anyone has recommendations. However, keep in mind that different people have different ideas of what makes a good fanfiction, so it might take some time to find ones that really resonate with you.
Archive of Our Own is a great place to start looking for 'yumi and sachiko' rated M fanfiction. It has a large collection of fan works, and its tagging system makes it easier to search for specific types of stories. Another option could be FanFiction.net, though their rating system and content availability might vary. Also, some smaller, niche fanfiction communities related to the characters or the source material they come from might also have such works, but they could be harder to find.
Some Tumblr blogs also post or reblog yumi x ulrich fanfics. You can search for relevant tags like #yumi x ulrich fanfic or #yumi and ulrich. It might take a bit more effort to find exactly what you're looking for compared to the dedicated fanfic sites, but it can be a great source for unique and interesting stories.
One common theme is friendship. Since Muffet can interact with various characters, many fanfics explore the friendships she forms. For example, she might befriend a character who is initially afraid of spiders but over time they become good friends.
The theme of love against all odds is also quite prevalent. Given their different origins and the fact that Goku is already married in the original story, their relationship in fanfics has to overcome many obstacles. This could be social, moral or even physical (like dealing with other powerful characters who oppose their union), but they still find a way to be together, which makes for an interesting read.
Another theme is self - discovery. Samus is a complex character, and fanfics often explore how she grows and learns more about herself. It could be about her coming to terms with her past or her role in the galaxy.