Well, the plot could involve his teammates having to take care of him. They might struggle at first because Kuroko as a baby can't communicate in the same way. Maybe they have to figure out his needs like when he's hungry or sleepy. And they could also try to keep it a secret from the other teams to avoid any distractions during games.
One possible plot is that the transformation into a baby is caused by a strange basketball-related accident. His friends would then need to find a way to reverse it. In the meantime, they'd experience all kinds of chaos. For example, Kuroko in baby form might still show an interest in basketball, like trying to grab a mini basketball or imitate shooting motions. This could be both cute and challenging for those around him.
The plot could be centered around how Kuroko's personality remains somewhat the same even as a baby. He might be unusually calm compared to normal babies. His friends could try to teach him basic things like walking and talking, but he might show a natural talent for basketball skills in a very innocent and endearing way. They would also have to protect him from any potential harm in the basketball world where there could be rivals who might take advantage of his vulnerable state.
Well, one possible plot could be that the other characters in the story are initially shocked. Papyrus might be super confused but also determined to take care of his 'baby' brother. They could go on little adventures where Papyrus has to protect Sans from various threats in the Underground while also trying to figure out how to turn him back to normal.
One possible plot could be that the magic in the world goes haywire. Natsu is caught in a spell that turns him into a baby. His friends in Fairy Tail are shocked at first. Lucy might take on the role of a caretaker, trying to figure out how to reverse the spell while also dealing with a baby Natsu's unpredictable behavior like randomly using small bursts of fire magic that are more like cute little puffs now.
The story could start with some sort of strange experiment gone wrong that turns Junkrat into a baby. The rest of the crew is shocked at first. Mei could use her scientific knowledge to try and find a way to reverse the process. Meanwhile, Reinhardt might tell stories to baby Junkrat about their adventures, as if he can understand. And Lucio could play some soft music to keep the baby calm.
In a 'kuroko turns into a girl fanfic', perhaps there's a magical event that causes the transformation. Kuroko, as a girl, could discover new aspects of his/her personality. For example, he/she might find that he/she is more in touch with emotions or has a different sense of style. And there could be a whole story about how he/she tries to fit into this new body while still maintaining his/her old relationships and goals.
Kuroko as a baby is the central character. But other characters from the opposing teams could also be important in an unexpected way. Maybe a rival team's player discovers Kuroko's situation and has a change of heart, deciding to help rather than take advantage. And of course, Kuroko's schoolmates who are not on the basketball team might also get involved, adding a different perspective to the story as they are not as familiar with Kuroko's basketball skills but still care about him as a person.
Well, one possible plot could be that Jimmy's latest experiment goes wrong and he is turned into a baby. His friends, like Carl and Sheen, would be really confused at first. They might try to figure out how to reverse the process. Meanwhile, Jimmy as a baby would still have his super - intelligent mind, but be limited by his baby body. So he could be using baby - like actions to communicate his scientific ideas to his friends, like babbling and pointing at things he needs for a new experiment to reverse his condition.
In this fanfiction, it could be that a magical accident occurs during a potion - making class. Harry accidentally drinks a wrong potion which transforms him into a baby. Dumbledore then decides to keep Harry at Hogwarts, with the teachers taking turns to look after him. Meanwhile, Neville could be the one who discovers a clue about how to reverse the transformation by observing some strange behavior of magical plants in the school's greenhouse.
One possible plot could be that Sirius accidentally casts a spell that turns Harry into a baby. He then has to take care of Harry in this new form while trying to find a way to reverse the spell. He might face challenges like hiding Harry from the wrong people, and also dealing with Harry's baby - like needs such as feeding and changing diapers.
The plot could center around the mystery of how Ciel turned into a baby demon. There could be a search for a way to reverse it. His allies, like the Phantomhive servants, would be in a tizzy trying to keep him safe and figure out what happened. Ciel himself, despite being a baby, might still have some of his old memories and try to communicate in his own baby - like way, which could be really cute yet frustrating for those around him.
One possible plot could be that the magic backfires on Voldemort during a powerful dark spell. As a baby, he has no memory of his previous self. The wizarding world is in chaos as they don't know what to do with this baby - voldemort. Some might want to kill him immediately, while others think he could be redeemed. Harry Potter, having defeated him once, feels a strange sense of responsibility and wants to make sure he doesn't grow up to be evil again.