Honestly, it's really hard to say who the author could be. There are so many people writing fanfiction these days. It could be a young writer just starting out, or an older fan who has been writing for years. It could even be a group of fans who collaborated to write this particular 'dean finds a baby fanfiction'.
It could be an established fanfiction writer who has written a lot about the same universe and decided to add this new plot of Dean finding a baby. They might have been inspired by other similar stories where a character discovers a baby in an unexpected situation.
There could be many potential authors. It might be a fan who loves the character of Dean and wanted to create a unique story around him finding a baby. It could be someone who is new to fanfiction writing and thought this would be an interesting scenario to explore.
Well, it could be that Dean stumbles upon a baby in some unexpected place like an abandoned building. He then has to figure out what to do with the baby, whether to find its parents or take care of it himself for a while.
The author could be anyone. It might be a fan who has been following the story of Zuko for a long time and thought it would be interesting to write a story where he finds a baby. It could also be someone who was inspired by other fanfictions or the original story and decided to put their own spin on it with this concept of Zuko finding a baby.
It could also be a group of fans who collaborated on the fanfiction. Each person might have contributed different ideas, like one coming up with the concept of Itachi finding the baby, another thinking about the setting, and someone else planning out how Itachi would interact with the baby in the story.
It could be an author who is known for writing about unusual character interactions in fanfiction. They saw the potential in Alastor's character and thought it would be interesting to see how he would react to finding a baby in Hell. This author might have a penchant for exploring the more tender or unexpected sides of characters in otherwise dark settings.
The baby could be an alien species that Goku has never encountered before. It might have special powers related to its alien origin, like the ability to control energy in a different way than Goku and his friends.
The baby could be an ordinary human baby that has some sort of latent magical ability that Raven senses. She then decides to protect the baby from the human world that may not understand or accept the baby's potential magic, and also from the magical world that might want to exploit the baby.
The baby could be an orphan from a nearby village that has been attacked. Kagome stumbles upon the baby while on her travels with Inuyasha. Since she has a big heart, she can't just leave the baby there, so she takes it with her.
The baby could be a lost elf child from a different part of the forest. Maybe their family was attacked by some dark force and Thranduil finds them by chance.
The baby could be a half - demon, related to some other important character in the series. Maybe it's the offspring of a character Sesshomaru has some history with.
The baby could be the child of a minor character from the original series who was in hiding. For example, the baby might be the offspring of a wizard who was on the run from Voldemort's followers and unfortunately didn't make it, leaving the baby behind for Harry to find.