From my point of view, it depends. If it's relating to the story and how some characters give off a certain energy or hints then I think its fine. Fan fiction is going to be a little bit too much for me
How dare you. Blocked, reported----nah, just kidding. Can you imagine though? (Sadly, I can. Twitter was not fun.)
Out of curiosity, if you're not joking what is your favorite Childe ship? I've never quite gotten into Childe as a character, so as a result I feel a lot of the fandom is so far away from me.