A unique idea could be that Percy and Thalia's wedding is a time - traveling event. They get married in different eras of the demigod world, experiencing the traditions of each time period. Another idea is that their marriage is part of a prophecy. The demigod world believes that their union will bring about a new era of peace and prosperity, so there are high expectations and a lot of pressure on them.
One interesting idea is that Percy and Thalia get married in a parallel demigod universe. In this universe, the rules are slightly different, and they have to adapt to new challenges while planning their wedding. For example, in this universe, the gods have a different role in the demigod's lives. Also, their wedding could be a magical event where the guests are all transformed into different mythical creatures for the celebration.
A really unique concept could be that Percy and Thalia's marriage is a result of a magical spell gone wrong. They were originally just friends, but a spell binds them in a way that makes them realize their true feelings for each other. As they try to break the spell, they end up falling deeper in love and decide to get married. Their wedding could then be a mix of trying to reverse the spell and also celebrating their newfound love.
One idea could be that Percy discovers he has a long - lost connection to Thalia. Maybe in a magical twist, a prophecy reveals that he is fated to be like a father figure to her. He could then use his powers and experience to train Thalia, much like Chiron trained him.
A plot could revolve around them having to protect a young demigod who is being hunted by a powerful enemy. Percy and Thalia have different approaches to protection, and they might argue at first. But as they face more danger, they realize that they need to work together. Their sibling relationship would grow stronger as they defend the young demigod.
One idea could be that they discover a long - lost family heirloom together. They go on a quest to figure out its significance and along the way, they face various monsters and challenges. It could strengthen their bond as siblings.
Perhaps a fanfiction where Percy and Thalia are transported to an alternate dimension. In this new world, they have to figure out how to get back while also dealing with different versions of their friends and enemies. Thalia might have to face an alternate version of herself who has turned evil, and Percy could be the one to help her see the light again. It would be full of action, drama, and self - discovery.
One idea could be Percy and Thalia teaming up to protect a group of young demigods who are being hunted by a new and powerful monster. They could use their combined skills, Percy's water powers and Thalia's electric ones, to fend off the attacks.
One idea could be that Thalia and Percy are on a dangerous quest together. In the middle of it, they find a mysterious lemon - themed garden that has magical properties. The lemon trees might have fruits that can heal wounds or give them special powers. They have to protect this garden from monsters while also exploring their feelings for each other.
Maybe they are all transported to an alternate dimension where the rules of their world are different. Percy has to figure out how to use his powers without water, Thalia discovers new aspects of her lightning, and Nico has to deal with different types of underworld creatures. They must find a way to get back home while also helping the people in this new dimension.
One idea could be that they discover their twin bond gives them unique powers. For example, they can combine their skills in combat, like Percy's water control and Thalia's lightning, to defeat a powerful enemy. Another plot could involve them exploring their family history together, finding out secrets about their parents that change their view of themselves. Maybe they meet a relative who knew about their twin relationship all along but was sworn to secrecy.
One possible plot twist could be that Percy and Thalia initially resist the arranged marriage. Percy might be in love with someone else, like Annabeth. But as they are forced to spend time together for the sake of the arranged union, they start to discover each other's hidden qualities. Thalia could reveal her vulnerable side to Percy, and Percy could show his loyalty and courage in a new light to Thalia. This could gradually lead to them developing real feelings for each other, despite their initial reluctance.
There are many possible plot ideas. For instance, in a fanfiction, Percy might get injured during a fight, and while Thalia is taking care of him, he realizes the depth of his feelings for her. Or it could be that there's a magical influence that makes Percy fall in love with Thalia, and they have to figure out if it's real love or just magic. Also, the idea of them being from different camps (like Camp Half - Blood and Camp Jupiter) and their love having to overcome the differences between the two camps could make for an interesting plot.