I was thinking of general stuff like canon discussion, sharing and reccing, commenting etc. I don't think any of them are essential, but they're recurring elements. It's interesting how the platforms shape fandoms that adopt them. I think people are heavily influenced by the kind of fandom that they find first, so each group that discovers online fandom on a different platform is a different "generation" of sorts with different priorities of fannish, uh, of expressing their fannish-ness? And then you have those who switch over from the "old" platforms who can have difficulties adjusting. But the way fandom constantly develops is one of the interesting things about it :)