I don't have problems with fanfics if they are based on tv series or cinema shows (not based on published books)as the media is different. I feel differently on fanfics based on published novels as it can affect the writer's income. After all, if there is a wealth of *good* fanfics written, readers might be less inclined to purchase the actual books written by the author themselves, which also affects not only the pro writer but also the investment of the publishers too.