Well, a cool plot might involve Natsu being transported to a parallel world where he is the only water dragon slayer. He has to adapt quickly to this new role and use his skills to fight against an evil force that is draining the water from that world. Also, he could meet alternate versions of his friends and have to convince them to trust him, since his powers are so different from what they know.
One idea could be Natsu exploring a new magic ability related to his dual dragon slayer powers. For example, he discovers a way to combine the fire of his Igneel - taught magic with the other dragon's element in a more powerful and unique way.
One plot idea could be that Natsu discovers a new, hidden power within his Alph Dragon Slayer abilities. Maybe he can communicate with ancient dragons that were previously unknown. Another idea is that he has to compete in a tournament against other dragon slayers with unique powers. This would lead to intense battles and character development.
One idea could be Juvia discovers a new water - based magic that only water dragon slayers can use. It gives her the ability to transform water into different forms, like crystal - like structures for defense. Another could be a time - travel plot where Juvia goes back in time and meets the first water dragon slayer and learns ancient techniques from them. And a third idea is that Juvia has to team up with other dragon slayers to defeat a powerful water - based villain who is misusing water magic and causing chaos.
A great plot could be about Natsu and the ice dragon slayer (let's say a new character) teaming up to defeat a powerful dark wizard. They have to overcome their differences in magic types and personalities at first. Maybe the ice dragon slayer has a cold and reserved nature compared to Natsu's hot - headedness. As they fight together, they learn from each other and create new combined attacks. For example, Natsu could use his fire to heat up the air around the ice dragon slayer's ice attacks, making them more powerful and unpredictable.
Perhaps a plot where Natsu and Wendy are transported to a parallel world where their roles as dragon slayers are completely different. In this world, they are the only hope against an evil dragon that has enslaved all the other dragon slayers. They must quickly adapt to this new reality and use their sibling bond to figure out how to defeat the dragon.
In some fanfictions, Natsu might have different dragon slayer magic elements. Instead of just fire, he could have a combination of fire and lightning, which would make his attacks even more powerful and unique. Also, there could be stories where Natsu travels to different dimensions or time periods, which would introduce all kinds of new challenges and adventures for him. This could lead to him meeting alternate versions of his friends or even new characters.
One idea could be Natsu learning new lightning - based attacks from a mysterious dragon. He could then use these attacks to defeat a powerful dark guild that has been terrorizing the region. Another plot could involve Natsu teaming up with other dragon slayers to face a threat that is immune to normal dragon slayer magic.
In 'natsu is the alpha dragon slayer fanfiction', an interesting plot point could be his relationships with other characters. Since he is the alpha, other dragon slayers might look up to him or be jealous of him. This could create complex dynamics, especially with his friends like Gray and Lucy. Natsu might have to prove himself not just in terms of power but also in his ability to lead and bring the group together in the face of danger.
One possible interesting plot point could be Natsu's unique powers as the alpha dragon slayer. Maybe he has enhanced strength or special abilities that set him apart from other dragon slayers. For example, he could have a more powerful form of dragon roar.
One common theme is power and growth. As Natsu becomes a water dragon slayer, he has to learn to control his new powers, and the fanfictions often explore how he grows stronger. For example, he might face challenges that force him to adapt quickly.