A plot could be set where Tigerclaw gets injured and is found by Leo. Leo decides to nurse him back to health despite the warnings of his comrades. As Tigerclaw recovers, they start to share stories of their pasts, their hopes and dreams, and gradually a relationship develops between them.
Maybe in the fanfiction, there is a prophecy that involves Tigerclaw and Leo. They are initially skeptical but as strange events start to unfold around them, they are forced to work together. Along the way, they face many challenges like distrust from their own sides, but their growing friendship helps them overcome all that.
One idea could be a story where Leonardo and Tigerclaw are forced to team up temporarily to defeat a common enemy greater than their rivalry. Maybe a new, powerful mutant emerges that threatens both the turtles and Shredder's plans. This would put them in a situation where they have to rely on each other's skills.
Maybe they discover an ancient prophecy that involves their union in some way. This could lead to a journey where they have to figure out what it means and face various challenges along the way. For example, they might encounter an enemy who is trying to stop them from fulfilling the prophecy. They start to develop feelings for each other as they go through these trials.
One interesting plot could be their unlikely alliance. Maybe in a story, they are forced to work together to face a common enemy that threatens the whole clan. This could lead to a lot of tension as they have to put aside their differences.
Another interesting plot could be that the reader is a time - traveler from the future. They come back to the present day and meet Leo. Leo is initially suspicious but as they work together to prevent a future disaster that the reader knows about, they fall in love. It adds an element of mystery and adventure to the story. Plus, the time - travel aspect can bring in different versions of the TMNT universe and how they interact with the current situation.
One idea could be that as a girl, Leo has to face different challenges in leading the team. Maybe she has to deal with more doubts from others at first because she's female. But she overcomes them with her skills and determination.
Perhaps a plot where Leo discovers some new powers or abilities that are related to his pregnancy. It could be something that he has to learn to control quickly. And then there could be a story arc about the team finding a way to ensure a safe delivery for Leo, which might involve seeking out some very rare or magical items.
One idea could be Taylor and Leo teaming up to solve a mystery within the lab. Maybe they discover a hidden project that could change the future of the lab rats. Another plot could be a love triangle situation where Taylor has feelings for Leo, but Leo is focused on his friendship with the lab rats and their missions.
One idea could be that Percy and Leo team up to build a super - cool underwater vehicle using Leo's mechanical skills and Percy's knowledge of the sea. Another could be them going on a quest to find a lost artifact that has powers related to both fire and water. They could face challenges like sea monsters and mechanical traps along the way.
One plot idea could be that Leo and Janelle team up to solve a mystery within the lab. Maybe there are strange malfunctions happening and they use their unique skills to figure it out.
A great plot could be about Leo and Raph competing in a tournament that's not just about physical strength but also about strategy and wisdom. They start off as rivals in the tournament but soon realize that they need to team up to defeat the real threat, which is a group of villains who are cheating in the tournament. This would show their growth from competitors to comrades. Also, a story where they are separated from their other brothers and have to survive in a harsh environment on their own, relying only on each other's company and skills.