One plot idea could be that a group of dark mages kidnap Erza to use her as a bargaining chip against her guild. They know her strength and reputation, so they think they can force Fairy Tail to give up some valuable magical artifacts. Another could be that an obsessed fan of Erza's kidnaps her, believing that she can be 'tamed' and made to love him. This could lead to a story of Erza having to outwit this deranged individual while also trying to escape from his clutches.
Perhaps an ancient evil entity, newly awakened, kidnaps Erza because it senses her strong magical power. It wants to drain her magic to regain its full strength. Erza has to fight against this entity from within its lair, using her wits and whatever resources she can find. Along the way, she discovers some hidden truths about the entity's past and how it relates to the world of magic as a whole.
Another plot could involve a crossover with the Harry Potter world. Erza could be a transfer student to Hogwarts. Her magic, which is different from the wizarding magic, would create a stir. She might have to face off against Voldemort's forces while also learning about the magical world of wands and spells.
One idea could be a story where they accidentally swap bodies. This would lead to a lot of comical situations as they try to adapt to each other's lives. They'd have to deal with different relationships within their respective guilds or groups while also learning more about each other's personalities.
One idea could be exploring how Erza balances her pregnancy with her duties as a strong mage. Maybe she has to take a break from dangerous missions and feels a bit restless. Another could be the reactions of her friends in Fairy Tail. They might be overly protective or excited for her.
One idea could be an Erza Scarlet crossover with the world of Harry Potter. Erza could be a visiting wizard from another magical realm. She might attend Hogwarts for a while, and her combat skills could be put to use in the Triwizard Tournament, adding a new and exciting dynamic to the traditional challenges.
The story could end with Erza escaping on her own. She uses her incredible combat skills and strategic mind to break free from her captors. She then returns to Fairy Tail, where she is greeted with great relief and celebration. And she vows to find and punish those who dared to kidnap her.
Well, it could be about the OC growing up in the shadow of Erza Scarlet. Maybe he's trying to live up to her reputation as a great wizard in the Fairy Tail guild. He might face challenges that test his loyalty and strength, just like Erza did.
One plot idea could be that Elsa is kidnapped by an evil sorcerer who wants to use her ice powers for his own dark deeds. The heroes from her world then have to embark on a journey to rescue her. Another could be that Elsa is kidnapped by a group who think her powers are a threat and they plan to keep her locked away forever. However, her sister Anna discovers her whereabouts and tries to free her.
One plot idea could be that Cinderella is kidnapped by an evil sorcerer who wants to use her beauty for a dark spell. Her fairy godmother then has to enlist the help of the animals she befriended to rescue her. Another idea is that Cinderella is kidnapped by a jealous rival from another kingdom who wants to take her place at the prince's side. The prince then sets out on a heroic quest to find and save her. A third plot could involve Cinderella being kidnapped by a group of bandits who mistake her for a wealthy noblewoman, and she has to use her wits to escape.
One idea could be that they discover the pregnancy during a mission. Maybe they are in the middle of fighting some powerful enemy when Erza suddenly feels unwell and realizes she might be pregnant. It could add a whole new layer of drama to the story, with Gray being overly protective.
Perhaps they could go on a journey to find a safe place for their child to be born. Along the way, they discover new things about each other and their relationship deepens. They might encounter different magical creatures or places that test their resolve and love for each other.