There could be other magical creatures in addition to the fairies that are main characters. Maybe a talking animal that the 'Pet Boy' befriends and they team up. This creature could have unique abilities that help the 'Pet Boy' in his adventures in the Fairy Hills.
A great concept for 'Pet Boy of Fairy Hills' fanfiction could be a conflict between different factions in the Fairy Hills. The 'Pet Boy' could get caught in the middle of it. He might have to choose a side or find a way to bring peace. You could also introduce a mystery element, like a series of strange events happening in the Fairy Hills that the 'Pet Boy' is determined to solve.
Obviously, Natsu is one of the main characters. He is often the center of the action in these fanfictions. Then there are the female characters from Fairy Hills, like Lucy. She usually plays an important role, maybe as Natsu's partner or as someone who gives him advice on the mysteries of Fairy Hills.
Lucy is a very popular choice. Since she lives at Fairy Hills, there are a lot of possibilities for stories centered around her daily life there, her relationships with the other girls, and how she continues to grow as a mage.
Obviously, Natsu would be one of the main characters since the title mentions him. There might also be other Fairy Tail characters like Lucy, who could be his friend or love interest in the high school setting.
I'm not entirely sure, but I think there must be a shepherd as one of the main characters.
Since I don't know the specific story, it's hard to say. But it could be soldiers from the opposing sides, military commanders, or perhaps some local civilians who played important roles.
I don't have enough information to say for sure. It could be a story about a group of hikers, so the main characters might be those hikers exploring the hills.
I'm not sure as the information about the story is limited. But it could be a lone traveler who is exploring the hills. This person would be the main character and the story could be about his or her journey through the hilly area.
I'm not entirely sure without reading it specifically, but it's likely to have characters who are long - time residents of Linden Hills. There might be a local shopkeeper who knows all the gossip and secrets of the neighborhood.
Gray Fullbuster can often be portrayed as a bad boy in fanfiction. His cool and sometimes aloof attitude, along with his stripping habit which can be seen as a bit of a rebel trait, makes him a popular choice. Another one could be Gajeel Redfox. He was originally an enemy but joined Fairy Tail. His rough past and tough exterior give him that bad boy vibe.