Yes, there are quite a few out there. You can start by looking on fanfiction websites like Archive of Our Own. Just search for 'Rogue One Jyn Cassian kiss' and you'll find a variety of stories that explore their relationship and that moment of a kiss, from sweet and romantic takes to more action - packed adventures where the kiss is a pivotal moment in their story together.
Archive of Our Own (AO3) is a great place to start. It has a large collection of Star Wars fanfiction, and you can easily search for 'Rogue One Jyn Cassian kiss' specific stories.
One great nesta and cassian fanfic is 'A Court of Wings and Ruin' - inspired stories. They often explore their complex relationship in a really engaging way.
It could be about Jyn Erso continuing her fight against the Empire. Maybe she teams up with new allies and undertakes secret missions to undermine the Imperial rule.
One nesta and cassian short story could be about their first encounter. Nesta was in a rather prickly mood, but Cassian was immediately drawn to her. He tried to make small talk, but Nesta brushed him off. However, Cassian didn't give up easily. He kept finding excuses to be around her, and over time, Nesta started to see his good qualities.
The 'enemies - to - lovers' trope is popular. They start off with some tension between them which gradually turns into love. It makes for an exciting read.
One of the main themes is acceptance. Nesta has to accept Cassian's presence in her life, and Cassian has to accept Nesta as she is, with all her flaws. Also, the theme of adventure often plays a part. They might embark on various adventures that test their relationship and force them to rely on each other.
Another theme could be the challenges they face during the pregnancy. This might include nesta's health issues or cassian's concerns about being a good father. It delves into how they support each other through these difficulties.
There's a fanfiction called 'Nesta, Cassian and Azriel: Bonds of Friendship'. It focuses on the deepening friendship among them which gradually turns into something more complex and interesting. It's really good at portraying their individual personalities within the group dynamic.
Another reason is that they are both such interesting characters. Nesta is strong - willed and Cassian is charming yet tough. Writers can play with their personalities in fan fiction, creating unique and engaging stories. For example, they can put them in different settings or give them new challenges to face together, which is really appealing to readers.