One common theme is their shared experiences in Hawkins. They both have been through a lot in that town, and fanfictions often explore how those experiences bind them closer.
In the fanfic, their relationship could develop as they face the reactions of their friends and family. Some might be overjoyed, while others could be skeptical or even disapproving. How they handle these external pressures together can bring them closer or cause some friction, which all adds to the complexity and growth of their relationship.
Another plot could be that they discover some unexpected powers or abilities related to the pregnancy. For example, Nancy might start having premonitions about the baby's future or Jonathan could sense danger more acutely to protect his family. They then have to figure out how to use these new abilities while keeping them a secret from others.
Another theme is the exploration of their deepening feelings. As they get to know each other more, their kisses mark different stages of their relationship growth. For example, a first hesitant kiss might be different from a more confident, passionate one later on.
One common theme is the discovery of love. They might start as friends or just acquaintances, and through various events, they discover their love for each other which is then expressed through a kiss.
One common theme is adventure. Given their experiences in the show, fanfictions often take them on new adventures together, facing strange creatures or uncovering mysteries. Another theme is romance development. Writers like to explore how their relationship might grow deeper and more complex over time.
Another one is 'The Love That Grew'. It focuses on the early days of their relationship, how they first fell for each other. It's a very sweet and detailed account of their initial interactions and the spark that grew between them.
One great Jonathan and Nancy kiss fanfiction might be about a time - traveling scenario. They could be transported back to a significant moment in their relationship, like when they first met but with all their current feelings. And as they relive that moment, they share a passionate kiss that's different from the original, because now they know each other so much better. It adds a whole new layer of depth and emotion to their relationship.
One interesting plot could be that they share a kiss during a dangerous situation. Maybe they are in a spooky place like the Upside Down, and the fear and adrenaline make them realize their true feelings for each other, leading to a passionate kiss.
You can start by looking on popular fanfiction websites such as Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, and there's a good chance you'll find some great Jonathan x Nancy fanfictions there. Another option could be Fanfiction.net, though the content quality may vary more.