If in the era of federated social media, large tribes/collectives/factions will develop - which one would you join? (possibly with reference to SF e.g. Expanse, Star Trek, Dune)
None. The beauty of a federated system is that I can stay in my home and still interact with all of those groups should I choose. If using the local function is important to you, then whichever community you are interested in.
Risa is already my favorite community here, and it only started popping up regularly like, a week or so ago. I'm totally in the Star Trek tribe.
And now I am picturing a funky future cyberpunk world where there are actual gangs, organizations and even religions built around super random fan communities like that.
"I wouldn't go to that part of town at night. They say there's roaming gangs of femboys that beat you to death with stuffed blue sharks. They call themselves the 196's and it is said that they rule."
This reminds me of Rainbow's End by Verner Vinge, where fan communities become large and organized enough to have meaningful political clout (and their online flame war conflicts can have actual significant impacts on society) and of the Poseidon's Children books by Alastair Reynolds where ideas like "Panspermia" become post-religious life philosophies that people commit themselves to.
And I think of all the examples I can think of, I would join the Panspermians from Poseidon's Children. The idea that we could choose to have purpose and that our purpose could be spreading life to dead rocks throughout the universe, because it's beautiful and worthy and a living rock is much more precious than a dead one is something I could really throw myself into.