Have you ever read Doujinshi?

Besides the question, I also want to learn more about it, from what I can grasp, they are fan made, and are about the creators own personal or popular shipping between two characters from their favorite Anime/manga(all types)

But, this is just my own speculation. It might not be true

I've never read one and know the plot behind it, mostly because I don't want a lot of Anime. But I do think there interesting I guess?