A short guide to tagging characters in your fic on Ao3:

Your character tags should look like this: "Important Character/ Reader, Important Character, Reader, Other Key Character" (this lists all the relevant characters for the story, including both the Reader for anyone who wants to filter for or against reader-insert fics and the main side-character who isn't in the ship but has significant story appearance. It does not clutter the tags with minor characters so people searching the tags for that character aren't disappointed by fics that only mention their fave in passing)

They should not look like this: "Important Character/ Reader, Important Character, Other Key Character" (Reader/ OC/ self-insert not mentioned, so would-be readers can't filter)

Or like this: "Important Character/ Reader, Important Character, Other Key Character, Minor Character 1, Minor Character 2, Minor Character 3, Minor Character 4, Minor Character 5" (Reader is not tagged, and the minor characters appear only in passing and are not essential to your plot like Other Key Character is so anyone hoping for a fic about those characters is about to be very disappointed with you)