There probably is. Fanfiction communities are quite large and diverse. Try looking on platforms dedicated to the fandom that Ben and Rook are from. Some writers might have explored this relationship with a kiss scene in their stories.
You can anticipate a lot of emotional exploration. The kiss could be a turning point in their story. Maybe it's a moment of realization for one or both of them. There may be some drama or conflict related to the kiss, like how others in their world react to it. Also, the fanfiction might expand on their backstories to give more context to the relationship. Since it's fanfiction, the writer has the freedom to take the story in many different directions. It could be a sweet, romantic story or a more angsty one depending on the writer's style.
Yes, there are likely quite a bit. Fanfiction communities are vast and diverse. For a pairing like Ben and Rook, fans who are interested in their relationship often write stories exploring different aspects of it, from adventures they go on together to more emotional and personal interactions.
One possible plot could be that Rook and Ben go on an adventure to a new planet in the Ben 10 Omniverse. They encounter a strange alien species that has a unique power. Ben tries to use his Omnitrix to transform into an appropriate alien to deal with the situation, but there are some glitches. Rook, with his Plumber skills, helps Ben figure out what's wrong and together they overcome the challenges and make new friends among the aliens.
By having them face a common enemy. When they fight side by side against a powerful foe, they can learn to trust each other more and understand each other's fighting styles better.
The friendship between Ben and Rook is a big draw. In fanfiction, it can be explored in different ways, like in tough situations or during their downtime. Also, the alien - filled universe of Ben 10 provides a lot of scope for interesting stories. Writers can create new alien species or new powers for Ben's Omnitrix, and Rook's Plumber skills add another layer of complexity to the stories.
Another theme is growth. Both characters can grow and learn from each other. Ben might learn more about Rook's culture and values, and Rook can learn about Ben's more impulsive but brave nature. This mutual growth helps to strengthen their relationship in the fanfiction stories.
Another way is by showing their daily interactions. Like when they're just hanging out between missions, sharing stories about their different worlds. Ben could tell Rook about his adventures on Earth, and Rook could share stories about his Plumber training. This would make them understand each other better and grow closer. They could also have inside jokes that develop over time from these interactions. Also, having them train together to improve their combat skills would not only make them better fighters but also strengthen their relationship as they rely on each other during the training sessions.
One common theme could be the exploration of their relationship in different scenarios. For example, in some fanfictions, they might be facing a dangerous situation together which brings them closer. Another theme could be the development of their feelings over time, from just being comrades to something more romantic.