It depends on how the author of the fanfiction has developed the plot and the characters. They could have given Natsu some special power - up or a unique situation that makes him stronger than Gildarts. For example, the author might have introduced a new form for Natsu that gives him an edge in combat, or perhaps they've weakened Gildarts in some way for the sake of the story. However, in the original series, Gildarts is extremely powerful, so this is a significant departure in the fanfiction.
In the fanfiction, Gildarts could meet Natsu and Igneel during a time of crisis. Maybe their town is under attack. Gildarts would immediately jump into action, and Natsu would follow suit, with Igneel guiding Natsu from the side. Gildarts might be impressed by the way Natsu and Igneel work together, as if they share a single mind. They could communicate without words, and Gildarts would try to learn from their unique bond. After the battle, Gildarts would offer to train Natsu further, seeing his great potential enhanced by his connection with Igneel.
Well, one possibility is that Gildarts could share some of his powerful magic techniques with Natsu. Since Gildarts is a very experienced wizard, he might see the potential in Natsu and offer some tips on how to better control his fire magic, which is similar to Igneel's. Maybe he could also tell Natsu some stories about his own adventures that would inspire Natsu to become even stronger.
Natsu could try his all - out offensive with his most powerful fire attacks. He might start with his Fire Dragon's Roar and then quickly follow up with a combination of punches and kicks enhanced with his fire magic. Another strategy could be to use his environment. If they're in a place with flammable materials, he can set them on fire to create distractions or additional sources of power for his attacks.
Gildarts would probably win. He's one of the strongest mages in Fairy Tail. His magic is very versatile and his strength is off the charts. Natsu is strong, no doubt, but he's still young and has a lot to learn. In fanfiction, the writers might be tempted to make it a close fight, but realistically, Gildarts' skills and power level are much higher. He's faced much tougher opponents and come out on top.
There could be. However, it depends on how popular the concept of Naruto being Gildarts' brother is among fanfiction writers. Some concepts are more common than others in the fanfiction world. You may need to dig a bit deeper into the fanfiction communities or specific Naruto - Fairy Tail crossover sections to find it.
Well, it really depends on personal taste. Some might enjoy it because it combines two different fictional universes in an interesting way. If you like crossovers and are a fan of both Naruto and Fairy Tail (where Gildarts is from), it could be a great read.
Another theme is the exploration of new worlds. Sometimes Gildarts brings a new perspective on the Naruto world or vice versa. The fanfictions might take the characters on a journey to discover new places or understand different cultures within these fictional universes. This allows for a lot of creativity in terms of world - building and character interactions.
Well, it could involve Naruto finding out about his long - lost brother Gildarts. Maybe they meet in a strange new world that is a mix of the Naruto and Fairy Tail universes. They then team up to fight a common enemy using their combined powers.