One common theme is his struggle to fit in. Lemongrab has such a distinct personality compared to the other characters in Adventure Time, so a lot of fanfics focus on how he tries to be part of the community.
A great lemongrab lemon fanfiction could be one that delves into his past. Maybe it reveals why he is the way he is. It could show his early days in the Lemon Kingdom, his relationships with other Lemon people, and how those experiences shaped his rather strange behavior.
To write a good lemongrab lemon fanfiction, you need to understand the world he lives in. The Lemon Kingdom has its own rules and culture. Incorporate that into your story. Also, don't be afraid to add some humor. Lemongrab's actions can be quite funny if written well. For instance, you could write about him getting into trouble while trying to organize a lemon festival.
One popular 'Adventure Time Lemongrab Fanfic' is 'The Trials of Lemongrab'. It delves into his unique character, exploring his relationship with the other characters in Ooo. It shows how his strict and often comical nature can lead to both chaos and unexpected moments of understanding.