Actually, original fiction gives you freedom no other writing can.
Seconded. :foodndrink:
Zalphon, if you really want to write a book, it can't be fanfiction. With very few exceptions (like the books Bethesda is currently having written), you're not allowed to make money off someone else's world. You can attribute your inspiration to other people, and you can mention that you started writing in TES fanfiction in an introduction or something... but, unless it's criticism or parody, making money off someone else's work is copyright infringement, plain and simple.
Fanfiction and original fiction are two different beasts, but if you're really interested in writing a book, you should definitely try it. Original fiction takes a long time of preparation (I'm into the years mark on my first original book, and I haven't even finished it yet!), and a lot of devotion. But you have complete control over it. You make up the Lore. You make up the people. You make up the magic, and the mood, and the geography. World-building alone is a HUGE project, and you do have to do a little research to make sure things make sense (where should mountains and deserts go on a standard land mass? What kinds of problems do different kinds of governments usually have? How much agricultural land do you need to sustain a certain population in a medieval society?). It is a huge project, and it doesn't give you the built-in fanbase that fanfiction does, but it's also a whole lot of fun. And who knows, it might make you a little extra money too.
Fanfiction is for appreciating someone else's world. Original fiction is for creating your own. I suggest you do both. :dance: