Thread:KusaNin/@comment-35199425-20180404014657/@comment-25156300-20180404020905

Not at all. Your story can be about whatever you'd like.

Just keep in mind that causing changes to the canon story (to the point of bending it too far or breaking it), can lead to Mary Sue traits. But if your story is completely separate from the main story/characters, then you shouldn't have much to worry about.

For examples of various styles of stories, just take a look at other peoples' characters. There are plenty of OCs that do their own thing with a story (my characters, included).