One common theme could be friendship turned into something more. Given their relationship in the original context, it's likely that fics explore the development of deeper feelings between them.
Redemption might be a theme. If in the original story one of them has made mistakes, fanfic could explore how they redeem themselves in the eyes of the other. Also, adventure themes where they go on quests together and their relationship grows during those experiences are quite common. They might face challenges that test their bond and make it stronger in the process.
Love and friendship are also common themes. It could be a slow - burn love story where they start off as just friends or acquaintances and gradually develop deeper feelings for each other. Or it could be about a friendship that is tested by various challenges in their world. Some fanfictions also explore the theme of loyalty. Are they loyal to each other despite their differences? And how far will that loyalty go?
In terezi x gamzee fanfiction, the theme of acceptance is quite prominent. Terezi has to accept Gamzee as he is, with all his quirks and flaws. The theme of growth also exists, as they grow together as characters. Their relationship can be a catalyst for personal development. Moreover, the theme of loyalty is explored. How loyal are they to each other in different situations? And sometimes, there's the theme of mystery, as the writers create new storylines that add an air of mystery to their relationship.
One way to find 'gamzee x terezi fanfic' is to join relevant fan communities. For example, on Tumblr or Reddit, there are often groups dedicated to the fandom. Members might be able to recommend some great fics they've come across. Also, don't forget to check out the official forums related to the source material, as fans there could also point you in the right direction.
Some 'gamzee x nepeta fanfic' might focus on character development. Writers could show how their relationship evolves over time, perhaps starting as acquaintances and growing into a deeper bond. This could involve exploring their individual fears, hopes, and how they support each other through various challenges.
Common themes often revolve around exploration. Since Sonic is constantly exploring new areas in his games, and Gamzee can be seen as a character who is also on a sort of journey in his own story. There's also the theme of power dynamics. Sonic has his super speed and other abilities, and Gamzee has his own set of skills or characteristics. How these interact and whether one overpowers the other or they find a balance can be a recurring theme. And of course, there's the theme of cultural clash, as they are from very different fictional universes.
One common theme is friendship development. They often start off not getting along or having misunderstandings, and then gradually form a deep bond. For example, in many fanfics, Karkat's brashness and Gamzee's more laid - back nature initially clash, but over time they learn to appreciate each other's qualities.
There's a fanfiction called 'Terezi's Purple Perception of Gamzee'. It's an interesting take on how Terezi views Gamzee and how that perception changes over time. To find more, you can join relevant Homestuck fanfiction forums or groups. People there often share and discuss their favorite works about terezi x gamzee. They might also be able to point you to some hidden gems that are not as well - known on the mainstream fanfiction platforms.
I'm not sure of specific gamzee x terezi fanfiction titles off the top of my head, but you can try searching on fanfiction - dedicated websites. Fanfiction.net is also a possibility. You might find stories that show their relationship in different timelines or alternate universes, like a story where they grow up in a different environment and how that affects their relationship.
One common theme is the exploration of their different personalities coming together. Eridan is often seen as more brooding and Gamzee as more chaotic, so their interactions can be an interesting study.
A common theme could be the exploration of their different personalities coming together. Gamzee is a rather complex character and Jane has her own set of traits, so seeing how they interact and form a relationship can be a big theme.