Like, if you're writing fanfiction of something, its generally because you like it enough that you were inspired enough to want to build off it, or re-interpret something.
But can you really say you're respecting the Fate or Harry Potter or what have you that you like so much, if you turn it into a power fantasy harem?
And I mean if that's the kind of thing you enjoy reading, all power to you, just don't get giga defensive when people point out the negatives in the things you like.