One interesting story could be where Goku and Bulma go on an adventure together to find a new Dragon Ball. In this fanfiction, they face many challenges and along the way, they start to realize their feelings for each other are deeper than just friendship. It shows a different side of their relationship compared to the original series.
I really like 'Goku and Bulma's Unexpected Journey'. It has a great plot where they are thrown into a parallel dimension. There, they have to rely on each other more than ever. The author does a wonderful job of exploring their characters and how they interact in this new and strange situation.
One interesting fanfiction could be where Bulma and Goku have to team up to save the world in a unique way that wasn't shown in the original series. Maybe they have to travel to a different dimension together and face new enemies.
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.
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.
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.
A lot of 'dbz goku x vegeta fanfic' has the theme of redemption. Vegeta, in particular, has a complex past, and in these fanfics, his relationship with Goku can be a part of his path to redemption. Also, the theme of family is present as they both have families and their interactions can be influenced by their family values. There's also the overarching theme of the Saiyan pride that they both carry and how it affects their relationship.
In some fanfics, Goku and Android 18 could start as rivals but gradually develop a mutual respect and then an unexpected friendship. This could lead to them training together and learning from each other's fighting styles. For example, Goku could teach 18 some of his Saiyan techniques, and 18 could show Goku her precise and calculated combat moves.