I became interested in the idea of fandom when I was reading the book Girl Wide Web 2.0 for class. It has an article titled “Me/Her/Draco Malfoy: Fangirl Communitites and Their Fictions” by Jaime Warburton that talks specifically about teen girls and their roles in fan fiction. Although fandom wasn't a prominent point I focused on in my research, I think it will be very helpful for hers. (I have the book if you would like to borrow it, Victoria, since it will not be found anywhere online.)
I also wanted to look at the sources the author used to write this article to see if they might be any use to Victoria, and I think I found a few. (And of course, there are more listed in the book, but these are that I felt would be of the most benefit to Victoria that I could also find online.)
“Is there a fan in the house?: The affective sensibility of fandom” by L. Grossberg in The adoring audience: fan culture and popular media edited by L.A. Lewis. You can find it here or by searching on the library website.
“Fan Fiction Online: Engagement, critical response and affective play through writing” by A. Thomas. Australian Journal of Language and Literacy. You can find it here or on the library website.
“Blurring and breaking through the boundaries of narrative, literacy, and identity in adolescent fan fiction” in M. Knobel &C. Lankshear (editors) A new literacies sampler. You can find it here. I was only able to find this source on Google Books, so it only shows a preview of this particular article, but I still think there will be some useful information for you and I think it is very pertinent to your topic.
I also stumbled across this website which has already curated a list of articles regarding fan culture.
I hope this helps, Victoria!