My fireteam changes around a lot depending on who's online but I have 4 other people. All known in real life. I kicked one in the face. One was in a lot of my classes. Never met one of them. Another was in my Physical education class. I did try grouping with randoms I find but because of this godawful localised matchmaking system for tower and crucible I only ever find English people. And I can't tell what the hell they're saying.