One popular one could be 'The Turtles and Their Little Sister's Adventure'. It often focuses on how the turtles protect their little sister in the dangerous world they live in. They face off against their usual enemies like the Foot Clan while also teaching their sister important skills.
A really interesting tmnt little sister fanfiction is the one that delves into her backstory. It shows how she came to be a part of the turtles' family. Maybe she was an orphan they found, or there was some sort of mysterious connection that brought them together. This story details her growth and how she fits into the group dynamic.
There's a fanfiction where the little sister has a special power. In this story, she can communicate with animals, which comes in handy during their battles and investigations. The turtles initially don't know how to handle this new aspect of their sister but gradually learn to use it to their advantage.
The little sister could also be a key in uniting different factions in the TMNT universe. For example, she might befriend some of the Foot Clan members who are tired of Shredder's tyranny. Her innocent nature could make them see a different side of life. And with the help of her turtle brothers, they could work together to bring peace to the city. It would be a great plot twist and a way to explore new relationships in the TMNT world.
She could be the moral compass for the turtles. Since she's younger, she might see things in a more innocent way and remind the turtles about the importance of things like mercy and forgiveness. For example, when they face an enemy, she could persuade them to give the enemy a second chance.
Some fanfictions might introduce new characters as friends or allies of the little sister. For example, there could be a street - smart kid who helps the little sister understand the human world better since she's growing up in a rather unusual family. But the main focus always remains on the relationship between the turtles and their little sister.
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 possible story could be that the TMNT find their little sister feeling down one day. To cheer her up, they start a gentle tickling session. The little sister initially protests but soon erupts into laughter. It becomes a fun bonding moment for them all.
She could get kidnapped by the bad guys and the turtles have to rescue her.
Well, in a tmnt little sister story, the little sister might be an ordinary girl at first. But when she discovers the turtles' lair. She becomes intrigued by their world. She starts to learn self - defense from them. As time passes, she helps the turtles protect the city. For example, she uses her knowledge of the city's layout to guide them during a chase against bad guys.
One great 'tmnt human sister fanfiction' could be 'Sisterly Bonds'. It focuses on the unique relationship between the human sister and the turtles, with a lot of heartwarming moments as they face various challenges together in New York City.
A really interesting 'Regulus little sister fanfiction' might involve time - travel. Maybe she travels back in time and tries to prevent her brother from getting involved with the Dark Arts in the first place. She could meet young versions of other important characters like Sirius and James, and her interactions with them could change the course of the future.
There's a fanfiction where Ciel's little sister teams up with Sebastian in a mystery-solving adventure. This is really cool because it shows a different dynamic between them compared to Ciel and Sebastian. She has her own unique way of approaching problems and it makes for an exciting read.