Yes, there are quite a few out there. You can start by looking on fanfic websites like FanFiction.net or Archive of Our Own. Just search for 'DBS Goku x Bulma' and you'll likely find some interesting reads.
One factor is the exploration of their relationship in different scenarios. In the canon, they have a long - standing friendship. Fanfics can take this and expand it, like what if Goku developed romantic feelings for Bulma? Or how would they handle a crisis together in a more intimate way than in the show? Also, seeing how the authors incorporate the Dragon Ball Super elements like the new forms and powers into the story of their relationship adds depth and interest.
The existing relationships in the Dragon Ball series can be a hurdle. Goku is married to Chi - Chi, and Bulma is with Vegeta. So, the writer has to find a way to make the Goku x Bulma relationship believable without completely disregarding the established pairings.
A good Bulma x Goku fanfic often has well - developed characters. It should stay true to their personalities from the original Dragon Ball series. For example, Goku's innocence and love for fighting, and Bulma's intelligence and sass. If the writer can capture these traits while also showing their growth in the context of the fanfic, it makes for a great read.
Another storyline could be that Bulma creates a new device that has some unexpected side effects. Goku is the only one who can help her fix it, and during this process, they accidentally get sent to a parallel universe. There, they have to work together to find a way back home, all while their relationship blossoms in this strange new world.
I've heard of 'Goku and Bulma: Unlikely Bonds'. In this fanfic, it delves into how their friendship could potentially transform into something more. It has some really interesting plot twists that keep you hooked. The author does a good job of staying true to the original characters' personalities while exploring this new relationship dynamic.
I'm not sure if there is a specific 'Goku married Bulma' fanfic rated M. Fanfic content can vary greatly, and while there might be some creative and alternative storylines in the fanfic community, this particular combination might be quite different from the original story. It could exist, but it would be a deviation from the main Dragon Ball narrative.
There may be such fanfics in the vast world of fan - created content, but it often goes against the original storyline's intended relationships in the Dragon Ball series. In the official story, Goku is married to Chi - Chi, not Bulma.
A possible plot could involve Goku and Gine meeting in a parallel universe where the normal rules don't quite apply. They start off as strangers but quickly realize they have a lot in common. Their relationship could develop as they train together, learning from each other's fighting styles. Gine might introduce Goku to some unique Saiyan traditions that have been long forgotten, and together they become a powerful duo in this new universe.
Bulma and Goku are the main characters. Bulma is known for her intelligence and her somewhat feisty nature. She's not afraid to speak her mind, especially when she feels wronged. Goku, with his innocent and straightforward personality, sometimes doesn't fully understand the implications of his actions. In a 'bulma goku mistake fanfic', their contrasting traits are what drive the story. For instance, if Goku accidentally eats all of Bulma's special food meant for an experiment, her reaction based on her assertive nature and his reaction based on his cluelessness about the importance of the food can create a lot of drama and humor.