Just because you don't like it doesn't mean nobody else does, nor does it give you authority over what can and can't be written in fanfics. If this person wanted to write this, they had every right to. You don't have to like it.
What I find ironic is that in your first post, you admit it was just a fanfic and seem to imply that you don't have to get upset over it because of that. But you then, in your next few posts, start complaining about the story, going against what you said at the end of your first post.
Everyone had a different opinion on fanfics and we will not all like the same stories. None of our opinions on what makes a good story should govern what other people may want to write, so long as it isn't derogatory or bashing.
So if you don't like this story, then just stop reading it and find something else to do, like another fanfic to read or something.