The contrast between their characters makes it interesting. Leah is often portrayed as strong - willed and independent, while Caius has his own mysterious and powerful aura. When they kiss, it's like two different worlds colliding.
There's a fanfiction where Leah and Caius are forced to work together on a mission. As they face various challenges, their relationship develops. The kiss scene is really well - written. It starts with a hesitant touch, then slowly builds up to a deep and meaningful kiss that surprises both of them and changes the course of their relationship completely.
They could also be characters from an existing story or series that the fanfiction is based on. Maybe they were minor characters in the original and the fanfiction writer decided to give them a more in - depth relationship and the moment of the kiss to explore their potential.
There probably is. The 'Twilight' fandom is huge and very creative. Writers may come up with stories where Jacob and Leah share a kiss for various reasons. Maybe it's a part of an alternate universe story where their relationship takes a different turn. It could also be a way to explore unrequited feelings or a sudden change in their relationship in a fan - created plot.
The popularity might also stem from the fact that their relationship, as shown in the source material, might be ambiguous. Fanfiction writers can then explore the possibility of a romantic connection between them through a kiss. It gives fans a chance to see their favorite characters in a new light, in a romantic situation that wasn't fully explored in the original work.
It could be that Leah is a shy person and Nahuel is the more outgoing one. They meet by chance in a park. As they start to know each other better, Nahuel slowly breaks down Leah's walls. The kiss is a culmination of their growing connection, and after that, they have to figure out how to build a relationship with their different personalities.
One great place to find such fanfiction is on Archive of Our Own (AO3). There are many stories there that might feature Leah and Demetri sharing a kiss. You can search using their names and the keyword 'kiss' to narrow down the results. Another option could be Fanfiction.net, but AO3 generally has a wider range of works with different themes and interpretations.
I'm not sure there are many official fanfictions just about their kiss. But one could imagine that their kiss might be a moment of realization of deep feelings. Maybe it happened during a special adventure in the magical world of Shimmer and Shine. For example, Zac could have saved Leah from a tricky situation, and in the heat of the moment, their lips met, sealing a bond that was growing between them all along.
One possible plot could be that in an alternate 'Twilight' world, Leah realizes she has deeper feelings for Jacob. They start to bond over their shared experiences as werewolves. As they grow closer, a moment of passion leads to a kiss. This could then cause chaos in the pack as some members oppose their relationship while others support it.
You can start by looking on popular fanfic websites like Archive of Our Own (AO3). It has a large collection of various fanfics, and there's a good chance you'll find Caius ballad kiss fanfic there.