I am a member of a Discord server that was created as a place for a community to move to after the place where the community formed was shut down. (For some context, see here, although not exactly necessary for the question.) There are actually two servers, one with a slightly bigger population (intentionally kept separate from the second). We'll call the bigger one "Nostalgia", and the smaller "Rainbow". The average age of the users in the servers is between 15 and 23.
I am technically a moderator of the Nostalgia server - the only one aside from the creator of the server. I am a regular member of the Rainbow server (and so's the creator of the Nostalgia one).
Recently, there was just a situation in the Nostalgia server where two users were arguing over a topic. One was of the opinion that going to high school graduation was worthless; the other felt it was important. At this point, I wasn't online.
Now, neither of these two users are in the Rainbow server. While they're arguing in Nostalgia, a discussion starts up in Rainbow about how, essentially, they find one of the users arguing to be... annoying. There are calls for the creator of the server, who's hanging around, to ban them. She doesn't know what to do; she doesn't really want to step in and be "the mod", and especially doesn't want to ban anyone, but feels like she has to do something, as the complaints continue in the Rainbow server.
So, so as to do something, she posts a message in the Nostalgia server, with an "@everyone", giving a reminder to be polite, and not be mean, and that she doesn't want to ban anyone.
Now, in reaction to this, one of the users who is arguing posts a defensive "nobody's being mean here" message, and then continues the conversation that started this whole thing.
At this point, I come online.
What can I do to deescalate, from this point forwards?
This would ideally involve stopping the conversation as soon as possible, getting the smaller server to stop calling for one user's removal, and not to make any enemies. I'm friends with all of the users involved, although more so with one of the users arguing than the other.
Note: I have a self-answer with what I did, that I feel worked, but I'd be interested to hear other online deescalation tactics that may help in future, similar situations.