There could also be the 'protective - partner' trope. For instance, either Sonja or Christopher might find themselves in a dangerous situation, and the other steps up to protect them. This trope plays on their loyalty and friendship, and in some cases, can be a precursor to a deeper relationship.
A common theme could be camaraderie. Given their work together, many fanfictions might show how they build a strong bond through shared experiences on the job.
You can try looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms usually have a wide variety of fan - created stories, including ones about Sonja Percy and Christopher Lasalle.
One place to start looking for Christopher Lasalle and Sonja Percy fanfiction is on fanfiction.net. There are often many stories created by fans that explore different relationships and scenarios between the two characters.
I'm not sure specifically which 'Christopher Lasalle' you're referring to. There could be many people with that name. It could be a local hero in a certain community with his top stories being about his acts of kindness, like helping the poor or volunteering at local shelters. Or perhaps it's a character from a TV show or book, in which case the top stories would be related to the plotlines he's involved in.
Adventure is also a popular theme. Many fanfictions take Percy and Lasalle on exciting adventures, whether it's chasing down a criminal in a new and dangerous part of the city or going on a mission that takes them out of their comfort zone. These adventures not only test their skills but also strengthen their bond.
The 'fish - out - of - water' trope is also seen a lot. When Percy ends up in Thor's world or vice versa, they are both out of their element. Percy has to deal with the strange Norse landscapes and customs, while Thor might struggle with the modern - day world if he goes to Percy's. It creates a lot of comical and interesting situations in the fanfiction.
You can try some popular fanfiction websites like 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 lasalle and percy fanfiction there.
One great 'lasalle and percy fanfiction' could be the one where they go on an adventure together in a post - apocalyptic world. It really shows their friendship and how they rely on each other in tough situations.
The 'redemption' trope could also play a part. Maybe Percy has to redeem himself in some way to be worthy of dating Hestia, or perhaps Hestia has to make amends in the eyes of others for choosing to be with Percy. This can add depth to the relationship and the overall story.
The 'slow - burn relationship' trope is also quite common. Writers like to build up the relationship between Percy and Reyna gradually. They might start with simple exchanges of respect and then over time, it could develop into something more romantic or at least a very deep friendship. In a lot of these fanfictions, it takes many chapters for them to truly understand each other on a deeper level.