Well, it could be about Natsu suddenly finding himself in a situation where he has multiple dragon companions who are all attracted to him. Maybe he has to deal with their different personalities and powers while also trying to figure out how he got into this harem situation in the first place.
Well, it could be about Natsu's journey to becoming a Dragon God and how he attracts a harem along the way. Maybe he gains new powers that make him irresistible to certain characters.
In addition to Lucy and Erza, there could be other female characters from the series. Maybe some minor characters who have always admired Natsu from afar. For example, that one girl from the guild who always blushes when Natsu is around. Another possibility is a powerful female dragon who sees Natsu's transformation into a Dragon God as a sign of his worthiness. She might join his harem, bringing a different kind of relationship dynamic as she has her own dragon - like qualities and power. And there could be a female mage from a different guild who hears about Natsu's new status and is intrigued, eventually becoming part of his harem.
Maybe Natsu discovers a new magic spell that accidentally turns him into a dragon. He then has to figure out how to reverse it while dealing with the new powers and instincts.
There could be a female dragon named Ignis who is very fiery and passionate, always trying to be the closest to Natsu. Another could be a more gentle dragon named Aqua, who has water - based powers and uses her calm nature to balance out the more intense dragons in the harem.
One possible plot could be that Natsu is cursed by a dark wizard. This curse slowly transforms him into a fire dragon. As he changes, he struggles to control his new dragon - like instincts and powers. His friends initially fear him but then realize they need to help him break the curse.
Well, perhaps the plot could involve Natsu's transformation being a result of some powerful magic or a dark curse. He might struggle to control his new dragon form at first, causing chaos among his friends and allies.
Well, perhaps the story could start with Natsu having a strange encounter that begins his transformation into a dragon. Maybe he discovers some ancient magic or a hidden power within himself that is related to dragons.
One possibility is that Natsu discovers some ancient dragon magic that transforms him into a Dragon King. He might gain new powers like the ability to control all types of dragons or access to long - lost dragon knowledge. This could lead to him having to face new enemies who are threatened by his new - found status.
Maybe it could involve Natsu having to go through some really tough trials to prove himself worthy of becoming the Fire Dragon King. For example, he might have to battle powerful enemies that are related to the dragon world's ancient secrets.
Well, perhaps Natsu could be turned into a vampire during a battle with a powerful dark magic user. Then he'd struggle with his newfound vampiric instincts, like the urge to drink blood, while still trying to be true to his friends and his guild.