One of the funniest scenarios could be when Happy tries to 'help' Natsu cook but just ends up making a huge mess. He might accidentally add too much of an ingredient or knock over pots while flying around the kitchen in excitement.
There's a fanfiction called 'Happy and the Lost Treasure'. In this story, Happy teams up with some unlikely allies in search of a legendary treasure. It has a lot of humor as Happy's antics keep the other characters on their toes. The story also has some really cool action scenes where Happy uses his flying skills to outmaneuver enemies.
Maybe they leave because they want to search for answers about their pasts. Happy might want to know more about his origins, and Lucy could be seeking something related to her family's history.
Archive of Our Own (AO3) is also a great place to look for 'Fairy Tail Happy' fanfictions. It has a well - organized tagging system. So, if you search for the 'Fairy Tail' tag and then narrow it down to stories involving Happy, you'll be able to find some really good ones. There are often high - quality stories there with unique takes on Happy's character.
One possibility is that they leave to explore a new land filled with unknown magic. They might be on a quest to find a powerful magic item that could help Fairy Tail in the future.
The unique character of Happy. When he's sassy, it adds a whole new dimension to his character. His sassy remarks are often unexpected and can be really funny.
One interesting aspect could be the unique character interactions. In fanfiction, the relationships between the characters from 'Fairy Tail' can be explored in new and unexpected ways. For example, Happy's character might be developed further in a roasting scenario, showing a different side of his personality. Maybe he gets into comical arguments with other characters, which can add a lot of humor to the story.