Here's your reminder that consent exists between internet friends and strangers as well, and I've seen a lot on AO3 where people will break that consent, so just to reiterate those lines of consent on the ends of both readers and CCs:
Posting stories with major triggers (rape/non-con, death, graphic violence, underage) and tagging it with "No archive warnings apply"? That is not consensual. You're telling people your story does not contain those triggers and still exposing them to said triggers.
Leaving comments, kudos, and other interactions on (a) fic(s) whose author has blocked you on other sites and/or has told you not to interact with them anymore? Especially guilting them and leaving comments about when they'll talk to you again? That is not consensual. Don't force your way into someone else's life. Just because they can't block you there doesn't give you the right to make their own spaces unsafe for them.
Reposting, translating, or remixing other fanworks without permission? Using other people's OCs or ideas when you weren't given permission to do so? That is not consensual. This should go without explanation.
Unsolicited advice and criticism? That is not consensual. Not everyone who posts wants advice, or maybe not even YOUR advice. If you can't say something nice, keep your opinions to yourself.
Writers have the permission to take back a gift they made and reclaim it as their own fic, just as the readers receiving it have permission to refuse that gift. It's consent, and that goes both ways. If someone removes a gift to you? It's not your place to start commenting and claiming it as your own. The same goes for turning down a gift.
And just as you're allowed to click off a fic without commenting, authors are allowed to delete those comments. Again, it's their space, and that's their choice to make.
And if you don't like something? You don't have to comment or kudos. Given that the story was properly tagged, your consent was given the moment you clicked onto that fic. Authors are not responsible for you choosing to spend your time on their fics when they've already informed you of what's inside.
The volunteers and the organization running AO3 is already doing so much for us, and they've been amazing at it, but there's still only so much they can do as an archive. Don't make fandom an unsafe place for people to create. If they set boundaries with their own works and accounts, they set boundaries, and those aren't there for you to break.