One common theme is the 'forbidden love' aspect. Since they come from different backgrounds and have different allegiances in the Marvel universe, their love can be seen as something that goes against the norm. This adds an element of tension and drama to the stories.
The theme of sacrifice also often appears. They might be in a situation where one has to sacrifice something for the other, and the kiss becomes a moment of bittersweet goodbye or a promise of a future together. It shows the depth of their love and how far they are willing to go for each other.
Adventure is also a big theme. Since they are both from the Guardians of the Galaxy universe, they often go on exciting quests together in fanfiction. This could involve fighting against powerful villains or searching for rare and valuable items across the cosmos.
One common theme is love and sacrifice. Since their relationship is complex, many fanfictions explore how much they are willing to sacrifice for each other.
One of the main themes is definitely the idea of second chances. Given their story in the movies, fanfiction often plays with the concept of them getting another shot at their relationship. The theme of sacrifice also pops up a lot, as both characters are known to be selfless at times. And of course, the theme of discovery, as they discover more about each other and themselves through their interactions.
Love and attraction can also be a theme. Given their different personalities - Peter's quick - wittedness and Gamora's strength - there is often an exploration of a romantic or at least a strong emotional connection between them. Some fanfictions focus on how they first notice each other, how they get to know one another better, and how their relationship evolves over time.
Another theme is the idea of finding love in unexpected places. In the vastness of the galaxy, they find each other and the kiss is a sign of that special connection. It also often involves themes of redemption, as both characters have their own past mistakes and the love they find in each other can be seen as a form of redemption.
One common theme is the exploration of their relationship. Since they have a complex dynamic in the movies, fanfictions often delve deeper into it. Maybe they're falling in love in a different way or facing challenges as a couple that the original story didn't show.
In Peter x Gamora fanfiction, the theme of cultural exchange is quite common. Peter represents Earth culture while Gamora is from a very different alien culture. Their relationship can be a vehicle for exploring how different values, traditions, and ways of life interact. Additionally, the theme of sacrifice often appears. Given the dangerous situations they face, either Peter or Gamora might be put in a position where they have to sacrifice for the other, which adds depth to their relationship.
One common theme could be forbidden love. Maybe they are from different social groups or have some sort of obstacle in their relationship that makes their kiss all the more intense.
Love and attraction are very common themes. Since it involves a kiss between Peter and Ava, the idea of their mutual affection is central.
One popular fanfiction site to look for such stories is Archive of Our Own (AO3). You can simply search for 'Peter and Gamora kiss' there, and you'll find a variety of works. Some stories might focus on their relationship developing over different adventures in the Marvel universe, leading up to that special kiss moment.