One interesting plot twist could be when the magic from Fairy Tail interacts with the sins' powers in Nanatsu no Taizai. For example, if Natsu's fire magic somehow combines with Meliodas' full counter, creating a new and unexpected power. Another could be the characters being transported to the opposite universe and having to adapt. Like Lucy ending up in Britannia and having to deal with the Holy Knights while the Seven Deadly Sins end up in Fiore and face off against the dark guilds.
A really cool plot twist could be a magical artifact that was split between the two worlds. In the story, the characters from Fairy Tail and Nanatsu no Taizai could be on a quest to find all the pieces of this artifact. As they search, they start to realize that the artifact has the power to either save or destroy both of their worlds. Along the way, they have to overcome their differences and learn to work together. And perhaps there are traitors among them, who are actually working for an evil force that wants to use the artifact for its own dark purposes.
Well, for starters, Lucy and Elizabeth could become fast friends. They both have kind hearts and are often in need of protection, though they are also strong in their own ways. Natsu and Meliodas would probably be a chaotic pair. They both love to fight and eat, and would likely get into all sorts of adventures together. Their relationship could start as a friendly competition but grow into a deep friendship. Meanwhile, Happy and Hawk would probably bicker a lot at first over food, but then become good friends as they realize they have a common goal of helping their main characters.
One idea could be a crossover with another popular fantasy series, like 'Fairy Tail'. The characters from 'nanatsu no taizai' could meet the wizards from 'Fairy Tail' and have to work together to defeat a common enemy that threatens both their worlds. For example, they might face a powerful dark magic user who has the ability to corrupt the magic in both universes.
Meliodas is a very suitable character for crossovers. His powerful abilities and complex personality can bring a lot to the story. He could interact with other powerful characters from different series and either form alliances or rivalries. For example, if crossed over with a character like Naruto, his determination and fighting skills could be compared and contrasted.
Well, in 'nanatsu no taizai crossover archive fanfiction', one might expect to see different art styles or interpretations of the characters. For example, if it's a crossover with a modern - day setting, the characters could be drawn in a more contemporary style while still maintaining their core traits. It might also explore how the powers of the Seven Deadly Sins would fare in different fictional worlds.
Well, perhaps a great plot twist is that Naruto's immortality is actually a curse in the Fairy Tail universe. The magic there has a different set of rules, and his inability to die disrupts the natural balance. This could lead to him being hunted not just by villains but also by some of the more morally strict magic guilds. Also, imagine if Naruto discovers that his past enemies in the Naruto world are somehow connected to an ancient evil in the Fairy Tail world, and he has to fight them again in this new context.
One interesting plot twist could be Sakura having to adapt to Fairy Tail's magic system. Maybe she discovers a new form of her own chakra-based abilities that interact with Fairy Tail magic in unexpected ways. For example, her healing jutsu could combine with Fairy Tail's healing magic to create a super - healing spell.
One interesting plot twist could be that characters from Fairy Tail end up in the world of Legend of Zelda and they discover that their magic has a completely different effect. For example, Natsu's fire magic might interact with the magical elements in Zelda's world in a way that either helps or hinders their quest. Another could be that the Triforce has an unexpected reaction to the Fairy Tail mages' presence, perhaps granting them new powers or cursing them. A third plot twist might be that a major villain from Legend of Zelda teams up with a dark guild from Fairy Tail to take over both worlds.
The plot might involve a magical mix - up. Maybe the power - granting items in The Seven Deadly Sins world, like the Sacred Treasures, get scattered across the Avatar world. The characters from both series then have to search for these items. The Avatar characters with their bending abilities and the Sins with their unique powers would have different approaches to finding the treasures. This could lead to a lot of interesting interactions and conflicts.
One possible theme could be the clash of different moral systems. Since 'Nanatsu no Taizai' has its own set of values among the characters, when they cross over, they may face different ethical dilemmas.
Well, a great plot twist might be that the characters from Fairy Tail end up in the world of Fullmetal Alchemist and are mistaken for some sort of alchemical creations. They then have to prove that they are not and in the process, they discover that their magic has some strange effects on the alchemy in that world. For example, Gray's ice magic could freeze alchemical reactions in unexpected ways. Another plot twist could be that the Gate in Fullmetal Alchemist has a link to the Fairy Tail's Celestial Spirit World. So when someone tries to open the Gate, they accidentally open a portal to the Celestial Spirit World instead, and all kinds of chaos ensues as spirits and alchemists meet for the first time.