One interesting plot could be baby Luffy getting lost on an island and Law, being the smart and capable one, finding him. They then form an unexpected friendship and go on little adventures together on the island, like exploring a mysterious cave filled with strange creatures.
One interesting plot could be Luffy in an alternate universe where he becomes an admiral earlier in his journey. He might use his unique leadership style and devil fruit powers in new ways to uphold the navy's justice while still maintaining his core values of freedom and friendship.
One interesting story could be about baby Luffy trying to imitate Shanks' tough pirate ways. He might pick up a little stick and pretend it's a sword, just like Shanks' weapon, and start challenging the other kids on Foosha Village. It's really cute to imagine baby Luffy with his big dreams already starting to form under Shanks' influence.
One interesting plot could be Luffy seeking out Mihawk for special training to become stronger in order to face tougher enemies. Another might be Mihawk seeing a unique quality in Luffy that makes him question his own views on pirates. And there could also be a plot where they team up accidentally to face a common threat that neither could handle alone.
One idea could be that Law has a very specific reason related to a grand plan against the World Government. He believes Luffy's unique abilities or connections can help, so he 'kidnaps' him in a rather non - malicious way at first. Maybe he wants to use Luffy's Gear Fourth power for some kind of experiment or strategy.
One possible plot could be Baby and Deborah going on a cross - country adventure, with Baby's amazing driving skills coming in handy during various unexpected situations, like escaping from some bad guys who are after them for some mysterious reason.
Zoro would be an interesting character to pair with them. He could act as a protector. With his strong swordsmanship, he can fend off any threats while baby Luffy is exploring and Law is doing his medical research or whatever he is occupied with. Zoro's serious nature would also create a nice contrast to Luffy's innocent playfulness and Law's more calculating personality.
One interesting storyline could be about baby Luffy's first encounter with Shanks. Maybe he tries to steal Shanks' hat in a really cute and clumsy way, not fully understanding its significance yet. Another could be baby Luffy's attempts at learning to swim, which is difficult for him as a Devil Fruit user. He might get into all sorts of comical situations in the water before someone rescues him. Also, a story about baby Luffy making friends with the other kids in Foosha Village, and how his unique personality starts to shine even at a young age.
A possible plot in baby Rosalina fanfiction is that she befriends a lonely comet. The comet is usually shunned by the other celestial bodies because it's different. But baby Rosalina sees the beauty in it and they become friends. This story could teach about acceptance and friendship. And there could also be a plot where baby Rosalina has a dream of visiting a far - off galaxy and she tries to make that dream come true throughout the story.
One interesting plot could be Superboy discovers a baby with superpowers. He then has to protect the baby from villains who want to use the baby's powers for evil. Another could be that the baby is from another dimension and Superboy has to figure out how to send it back home while also keeping it safe in his world. Maybe the baby has a special connection to Superboy's origin that he has to uncover.
There are also plots where baby Stiles has some special powers that he doesn't have as an older character. The pack has to protect him from those who would want to use his powers for evil, and in the process, there are cute and heart - warming interactions between Stiles and the members of the pack as they try to understand his powers and keep him safe.