One common theme could be his struggle. Since Atsushi has a difficult past in the original story, in 'child atsushi fanfic', it might show his struggle as a child, like dealing with hardships in the orphanage.
One common theme is his self - discovery. Atsushi has a lot of insecurities and a troubled past, so many fanfics explore how he comes to terms with who he is. Another theme is friendship. His relationships with the other members of the Armed Detective Agency are often central, like how Dazai's mentorship affects him.
One common theme could be the rescue. Other characters might band together to save atsushi. Another theme could be atsushi's inner strength while being kidnapped, like how he copes with the situation mentally.
One common theme could be self - discovery. When Atsushi is hurt, he might have to face his inner fears and insecurities, leading to a journey of self - discovery. Another theme could be the bond with other characters. His hurt might strengthen or test the relationships he has with the members of the Armed Detective Agency.
One common theme is the OC helping Murasakibara grow as a person. Since he has his own quirks and insecurities in the original story, the OC can be written as a positive influence on him.
I'm not sure which specific 'child atsushi fanfic' you are referring to. But you can try searching on some fanfiction platforms like Archive of Our Own. There might be some interesting stories there.
Well, a recurring theme in 'child of artemis fanfic' is the struggle between the mortal and divine sides of the character. Being a child of a goddess means having certain powers and responsibilities, but also having to deal with the limitations of being part - human. Another theme is the pursuit of justice. Artemis is associated with justice in some ways, and her children in fanfics often strive to uphold what is right. And of course, the theme of sisterhood or brotherhood is there too, as they are part of a community of demigods related to Artemis.
A frequent theme in child Anakin fanfic is his life on Tatooine. This includes his experiences as a slave, his dreams of a different life, and the people he meets on the desert planet. Also, the idea of Anakin being a chosen one is often explored. How does he start to realize his special destiny? And how do others around him react to this potential? These are all aspects that are commonly written about.
A common theme is growth. It often shows how Natsu grew as a person and as a wizard during his childhood. Another theme is friendship. Since he was in the guild as a child, his relationships with the other members, especially his peers, are explored.
One common theme is growth. It shows how Mikasa grew from a child into the strong character she is. Another theme is family. Her family's influence on her as a child is often explored. For example, how her parents' teachings stayed with her.
One common theme could be friendship. If Sookie is a child, stories might focus on her making friends and the adventures they have together.