It's very possible. The world of fanfiction is vast and full of creative interpretations. Writers might be interested in exploring how the relationship between Ryuuki and Shuurei could develop in the context of a pregnancy. You should start your search on well - known fanfiction platforms. Keep in mind that different platforms may have different levels of popularity for different fandoms, so it might take some time and exploration to find what you're looking for.
Fanfiction.net is also a popular option. It has been around for a long time and has a huge number of fanfictions. Look for the relevant fandom category and then search for the specific plot of Ryuuki and Shuurei being pregnant within that category. You may also find some on Tumblr, where fans sometimes post their own fanfictions or reblog ones they like, but the search might be a bit less organized compared to the dedicated fanfiction platforms.
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.
Another option could be an alien from Starfire's home planet. This would add an interesting dynamic as the baby would have a strong connection to Starfire's alien heritage. It could also bring in some unique storylines about the alien culture and how it affects the baby's upbringing. Maybe the alien father has certain powers or responsibilities that are passed down to the baby.
The baby could be a really interesting mix. It might have Hermione's bushy hair and Legolas' pointed ears. And perhaps inherit Hermione's intelligence and love for books as well as Legolas' amazing archery skills and connection to nature.
Edward Cullen is one of the most common baby daddies in Twilight baby daddy fanfiction. Since he's the main male lead in the original series and has a complex relationship with Bella, it's natural that many fanfiction writers explore the idea of him as a father. Jacob Black is also a popular choice. His relationship with Bella was also significant, and in some fanfictions, he could end up being the baby daddy in an alternate storyline. Another character who might be the baby daddy in some fanfictions is Aro from the Volturi. His powerful and mysterious nature makes for an interesting take on being a father in the Twilight - inspired stories.