It depends on the specific fanfiction. While the base material of Dragon Slayer might not have Levy as a Dragon Slayer, in the world of fanfiction, all kinds of alternate storylines are possible. Some writers may see her character as having the potential to take on this role and create a whole new set of adventures and relationships around it.
I don't know for sure, but she is probably the main character in the 'betty knox ghost story'. Since it's named after her, she must be the one who has some kind of experience with the ghost.
Makarov, the guild master, could also be present. He might see Levy's sleeping as a sign of the guild's youth and innocence. He could be reminiscing about the early days of the guild while looking at her sleeping form, and then make decisions about the future of the guild based on those thoughts.
It's possible that Levy is getting emotional. If the story has a touching plot, like a story of sacrifice or friendship, Levy, who values her friends in Fairy Tail deeply, could be moved to tears or have a warm smile on her face as she reads on.
Gajeel could be a great character to pair with Levy. Their relationship has always had an interesting dynamic, with Gajeel starting off as a bit of a rough character and Levy being more gentle and studious. Another option could be Lucy. They are both female members of the guild and could have a story together where they go on an adventure and use their different skills to overcome obstacles.
It can show her vulnerability. Levy is usually seen as a smart and capable mage in Fairy Tail. But in an embarrassing naked situation, her confidence might be shaken, revealing her more vulnerable side. For instance, she may become shy and reserved, which is different from her normal assertive self when dealing with books and knowledge.
Betty Broderick was a woman who was deeply wronged in her marriage. She felt scorned when her husband had an affair and left her for another woman. Her story is one of a woman pushed to the edge by the actions and neglect of her partner.
The Gajeel and Levy lemon fanfic is likely to focus on their relationship dynamics. It could start with building up their friendship and mutual respect, which is a common theme in non - lemon fanfics about them as well. Then, as it progresses to the 'lemon' parts, it may be used to illustrate the ultimate level of closeness and trust between them. For example, it might show how Gajeel, who is usually rough around the edges, becomes tender and caring towards Levy in these more intimate moments. And Levy, in turn, might be shown as more confident and bold in expressing her feelings for Gajeel.
One great Levy and Gajeel fanfiction is 'A Bond Beyond Words'. It beautifully explores their relationship growth from rivals to lovers. The author does an amazing job of capturing Levy's intelligence and Gajeel's rough - yet - tender side.