I haven't read a specific fanfiction about their kiss yet. But I can imagine it would be really sweet. Maybe in the fanfiction, their kiss could be a moment of realization of their deep feelings for each other. It could happen during a dangerous adventure when they think they might lose each other.
Some dedicated fanfiction forums might also have stories about their kiss. These forums usually have a search function that you can use to look specifically for Class of the Titans fanfiction. However, be aware that the quality of the stories can vary widely, so you may need to read a few to find one that really satisfies your expectations.
One possible scenario in this fanfiction could be that Theresa is kidnapped by an old enemy of the Titans. The other Titans then embark on a dangerous mission to rescue her. They might have to face various challenges and puzzles along the way, as the kidnapper has set up many traps.
In the 'jay and lonnie kiss fanfiction', the kiss itself can carry a lot of significance. It could be a way to show their mutual attraction that has been building up over time. This type of fanfiction often gives fans a chance to explore relationships that they wish to see in the original story. It might also introduce new plotlines, such as how their friends react to this new development between Jay and Lonnie, or if there are any obstacles that come up after the kiss.
One idea for a Class of the Titans crossover fanfiction could be with the Percy Jackson series. You could have the demigods from Percy Jackson meet the heroes of Class of the Titans. Maybe they team up to fight a common enemy like a powerful Titan that has escaped from Tartarus. The different powers and personalities would make for an interesting dynamic.
Another theme is hope. The kiss between them can represent a glimmer of hope in a dark world. It gives the characters and the readers the feeling that there is still something good to hold on to, like in the fanfiction where their kiss is a sign that they can overcome the evil forces around them.
Common themes in Class of the Titans OC fanfiction include adaptation. OCs usually have to adapt to the new and dangerous world of the Titans. They come from different backgrounds and have to learn the ways of the Titans' school and their battles. Another theme is redemption. If an OC has made mistakes in the past, they might be seeking redemption. This could involve making amends with characters they've wronged or proving themselves worthy to the Titans. And the theme of destiny also plays a role. OCs may feel like they have a certain destiny in the world of the Titans, whether it's to become a great hero or to fulfill a prophecy.
One popular theme is the characters' relationships. For example, exploring the friendships between the members of the Class of the Titans in more depth, like how they support each other during difficult times.
I'm not sure of a specific Jay and Lonnie kiss fanfiction off the top of my head. But you could start by looking on fanfiction websites like Archive of Our Own. There are often many stories in the 'Descendants' fandom that might include such a scene.