A different plot could be that the reader has some sort of special power that Nightwing needs to help him in a big battle against a powerful super - villain. They team up, and during their time together, they discover they have a lot in common. The reader might be initially hesitant about using their power, but Nightwing encourages them, and this shared experience brings them closer together.
One interesting plot could be the reader helping Gaster with his scientific experiments in the Underground. It could show their growing bond as they work together and face various challenges in the lab.
A plot where the reader has some sort of special power or ability that Shigure is intrigued by can be really engaging. He might initially be interested in using that power for his own gain, but as he spends more time with the reader, he falls in love. Or perhaps a plot where the reader is sent to help Shigure with a personal problem, like dealing with a past trauma. Through their time together working on this, their relationship blossoms. There could also be a time - travel plot, where the reader is sent back in time and meets a younger Shigure, and they form a connection that spans different timelines.
A really interesting plot might be where the reader is from a different land and has a unique ability that Toothless is drawn to. Maybe the reader can communicate with dragons in a special way. Their relationship could develop as they use this ability to help Toothless and his dragon friends in some kind of threat or challenge that the dragons are facing in their world.
One plot idea could be that the reader is a new student at Hogwarts from a different magical culture, and Draco is initially intrigued and then falls for her as he discovers more about her unique magical abilities and traditions. Another could be that they are paired up for a difficult Potions project, and through their trials and errors in the project, they grow closer.
A really interesting plot could be set in an alternate universe where Gladion is a normal high school student and the reader is a new transfer student. The reader discovers Gladion's secret love for Pokémon battles which he has to keep hidden from his strict family. As they bond over this shared secret, a relationship forms between them. It would be a great way to explore Gladion's character in a different setting.
Another plot could involve the reader being a magical being, like a fairy or a witch, who is on a mission to protect Ciel from a dark magic that is threatening him. This would create a lot of opportunities for magical elements and a relationship that develops as the reader uses their powers to keep Ciel safe. They might have to go on quests together to find magical artifacts to counter the dark magic. It's a plot full of adventure and mystery.
One idea could be that the reader is a new ninja - in - training and Lloyd has to mentor them. They start off with a rocky relationship but gradually grow to respect and care for each other as they face various challenges in Ninjago.
A really cool plot would be if the reader - insert has the power to time - travel. They and Percy use this power to go back in time to prevent a great tragedy in the demigod world, like stopping a powerful villain from ever rising to power. Along the way, they face challenges in different time periods, like dealing with the ancient rules and cultures of the past while also trying not to disrupt the timeline too much.
Here's a more complex plot. The reader is an auror who is initially suspicious of Newt because of his association with some dangerous - looking magical creatures. But as they get to know each other better, the reader realizes that Newt is just a kind - hearted man trying to protect these creatures. They then team up to stop a group of dark wizards who are planning to use the magical creatures for evil purposes. During this adventure, their relationship evolves from mistrust to love. This kind of plot has action, mystery, and a developing relationship all in one.
One plot idea could be the reader being from another world and having some unique knowledge or ability that helps in the fight against Titans. For example, knowledge of advanced weaponry or strategic thinking that's not common in the Attack on Titan world.