What are some interesting plot ideas for tmnt baby sister fanfiction?

One idea could be that the little human sister discovers the Tmnt's lair by accident. Maybe she was exploring the sewers for a school project on urban infrastructure. Once there, she befriends the turtles and helps them out with some human - world tasks like getting supplies or finding information on their latest enemy.

One idea could be that the Turtles from 2003 get transported to the 2012 universe and they have to deal with the different versions of their enemies. For example, the Shredder in the 2012 version might have some new powers or tactics that the 2003 Turtles aren't used to.

A possible plot is that an ancient evil that was sealed away in the 2003 universe is accidentally awakened by the arrival of the 2012 turtles. The 2003 turtles initially blame the 2012 ones but then realize they need to work together. They combine their strengths, with the 2012 turtles' modern thinking and the 2003 turtles' deep knowledge of ancient ninja lore, to defeat the evil.

One idea could be that the Turtles from 1987 end up in the 2003 universe and have to adapt to the darker and more serious tone. They could team up with the 2003 Turtles to fight a common enemy like the Shredder. The 1987 Turtles' more light - hearted and comical ways might initially clash with the 2003 Turtles' brooding nature, but they eventually learn from each other.

One idea could be that Percy's baby sister discovers she has a unique power that even Percy doesn't have. For example, she might be able to communicate with the spirits of the ancient Greek heroes in a way that gives her special knowledge. Another plot could be that she gets kidnapped by a new enemy who wants to use her to get to Percy. Percy then has to go on a dangerous quest to rescue her, facing all kinds of mythical creatures along the way. A third idea is that she is actually a reincarnation of an important figure from Greek mythology, and as she grows up, she starts to remember her past life and the secrets it holds, which causes a stir in the demigod world.

One idea could be an OC who is a new mutant in the city. They could have a unique power like the ability to control plants. At first, they are scared and confused about their new form and powers, but as the story progresses, they learn to use it for good and join the turtles in their fight against the bad guys.

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 that Mikey and Shinigami team up to solve a mystery in the sewers that involves some strange magical creatures. They use Mikey's fun - loving nature and Shinigami's magic skills to figure things out.

One idea could be that the Turtles end up in the Underground world of Undertale. They might have to navigate through the various regions, like Snowdin or Hotland, using their ninja skills. For example, they could use their stealth to avoid some of the more dangerous monsters. Another plot could involve the characters from Undertale being brought to the Turtles' New York. They would then have to deal with the Foot Clan and other threats in this new, strange environment.