My thoughts about fan-fics and oc are that thier stories take place in a different universe from the normal canon equestia, say for example, your oc name is bob, and he is a pegusus who farts rainbows, and he is married to Rainbow Dash, even if you claim it is true and it happens after the show, that's your crazy little universe with whatever things you want in it, now here are some random examples-
-equestia girls universe, which is canon, it is The same as the show, but is a humanized vers