No thralls. You can tame a few animals a breed them. Mostly for their meat and pelts but some can follow you into combat.

I've only played solo. Didn't need a massive city. Nice cozy fort with a kitchen, bedroom, storage, portal room, a crafting area and some farm land. I use small outposts for things I couldn't grow at the homestead.

There are other npcs in the game. An unkillable trader with a few bibs and bobs and a couple of his friends later in the game you can kill if you so choose to. They buff ya and share common enemies but not much else.