Perhaps Robin's red color is a sign of his being chosen by a secret order. He then embarks on a journey to learn the ways of this order, facing various challenges and making new allies along the way. In the fanfiction, his red attire could hold special significance within the order's lore.
Another plot could be that Blackfire comes to Earth seeking refuge from some intergalactic trouble. Robin is the one assigned to protect her. At first, Blackfire resents the protection, but as time passes, she realizes Robin's good intentions and they form an unexpected bond. Their adventures on Earth, with Robin showing Blackfire the beauty and uniqueness of the planet, could be really engaging.
One idea could be to have Batman and Robin face a villain who has the power to manipulate time. They would have to figure out how to stop the villain from changing history. Another could be that Robin gets kidnapped by a new, never - before - seen criminal and Batman has to use all his detective skills to find him. Maybe a third idea is that a powerful alien lands in Gotham and Batman and Robin have to team up with other heroes to deal with it.
One idea could be a time - travel plot where Robin from the present meets a younger Lucina. They could initially be at odds due to their different understandings of the future and past events. But as they spend time together, they start to understand each other and develop feelings. Another plot could be set during a war where they have to fight side by side and rely on each other's skills. This shared experience could bring them closer. A third idea is a story where they meet in a peaceful village and help the villagers together. Through their acts of kindness, they fall in love.
A crossover with Harry Potter would be cool too. Robin Hood could find himself in the wizarding world and use his archery skills in a magical tournament. He might also team up with the Hogwarts students to fight against some dark wizards who are trying to steal magical artifacts hidden in Sherwood Forest.
In some 'batman fights robin fanfiction', there might be an external factor like an ancient curse that affects Robin. He becomes aggressive and unpredictable, forcing Batman to fight him. This could also be related to a prophecy that Robin is supposed to bring chaos, and Batman is trying to prevent it. Batman would be conflicted as he doesn't want to harm Robin but also needs to stop the potential danger.
Perhaps a plot where Starfire and Robin get married in a secret ceremony due to security reasons. But then they have to deal with the media finding out and all the chaos that ensues. This could involve protecting their friends and family from paparazzi and supervillains who might want to use the situation to their advantage.
One idea could be Batman teaching Baby Robin the basics of detective work. For example, showing him how to analyze crime scenes for clues. Another could be a story where they face a villain who specifically targets Robin because he's young and inexperienced. A third idea might be a heartwarming tale of Batman protecting Robin during a city - wide disaster.
In the fanfiction, the baby could have some unique abilities inherited from both Zoro and Robin. For example, it could have Zoro's sense of direction in combat and Robin's ability to read ancient texts. This could lead to many interesting adventures as the crew tries to understand and help the baby develop these powers.
One plot idea could be how they handle ruling a kingdom together after getting married. There could be political challenges and how they support each other through it. For example, dealing with rival kingdoms or internal disputes.
One idea could be that Robin discovers a dark secret about Batman's past that makes him question their relationship, leading to a tense confrontation. For example, if Robin finds out that Batman once made a deal with a villain that had far - reaching consequences. Another plot could involve a new villain manipulating Robin into believing Batman is a threat to Gotham, causing them to fight. Maybe the villain uses mind - control technology.