I'm building a fanfic archive and I've been thinking a lot about the limitations of AO3's tagging system lately. For me, the biggest issue is the lack of distinction between "main" and "side" characters/relationships.

If I want to read a fic where Character A is the protagonist, I have to filter for Character A—but then I get hundreds of fics where they're just a background cameo. Same goes for relationships.

I also wish I could filter out any relationship involving a character without filtering out the character themselves. Sometimes I'm too tired of seeing ships with A/{B, C, D...Z, X, Y}, but I don't want to exclude Character A altogether.

And sometimes I'd like to search for attributes like "BAMF" that apply to the main character, regardless of who that character is. If I search for "BAMF Character A," I can get fics where A is just a side character.

What limitations bug you the most? Have you found any workarounds?