The main characters are usually Itachi and Sakura, as the 'itasaku' in the name implies. And of course, their babies are central to the story as well.
In some itasaku babies fanfiction, other characters from the Naruto universe might also be important. For instance, Naruto could be a supporting character, perhaps as a godfather - like figure to the itasaku babies. Kakashi might also show up to offer his wisdom and guidance on raising ninja children.
One interesting plot could be the babies inheriting unique ninja abilities from their parents. For example, they might show early signs of Sasuke's Sharingan or Sakura's super strength.
The main characters are usually the baby versions of Sonic and his friends. So, there's baby Sonic, who is likely to be really cute and still have his signature speed, just in a more clumsy, baby - like way. Then there could be baby Tails, with his two little tails still being a prominent feature.
There could also be other characters like their parents or mentors who play important roles. The parents might pass on their wisdom and powers to the Big Chill Babies, and the mentors could guide them in their growth and development. So, in addition to the Big Chill Babies, these supporting characters are also key elements in the fanfiction.
Obviously, the babies of Kakashi's team 7 would be the main characters. So, there would be Naruto's baby, Sasuke's baby, and Sakura's baby. They are the focus as the story would revolve around their lives.
The main characters are not just limited to the ones we know from the original series. There could be some side characters from the village who play important roles. For example, a medical ninja who helps take care of the babies when they are ill or injured. Also, there might be a mysterious figure from another village who has a connection to the events surrounding Team 7's babies.
There could also be other characters like Tyrion. He might be involved in advising Jon and Daenerys on how to raise the children, or he could be helping to protect the twins from political intrigue within the Seven Kingdoms.
Obviously, Harry and Ginny are the main characters. They are the parents in this fanfiction, so a lot of the story will revolve around them.
Obviously, the Big Chill babies would be the main characters. They are likely to be the focus of the story.
Obviously, Ben Tennyson is one of the main characters. He is the central figure around whom the story revolves. And the 'babies' are also main characters, though who they are exactly can vary. They could be new alien forms that Ben discovers and takes under his wing, or they could be some sort of younger versions of himself or other characters related to the Ben 10 universe.
The main characters would be Wes and his babies for sure. But depending on the plot, there could be teachers or mentors from the local music scene. These characters could play important roles in the development of the babies' musical skills. For example, a strict but kind music teacher who helps the babies perfect their vocal techniques or learn new instruments.