I once traveled business-class in Qatar Airways. I am not sure about their seating policy. I was, however, able to choose my seat while I got my online boarding pass.
So, after I got in to the plane I noticed that the seats in front of and behind the one that I booked were unoccupied, and there was a gentleman in the aisle seat (I booked the window seat). So I went and sat down in my seat, because I wasn't sure if the other passengers would show up or not. I've read online that Qatar Airways has a free-seating policy (first come first served).
After a while, just before takeoff, he moved to one of the empty seats and remained there for the rest of the flight. I felt bad thinking that I should've done the same in the first place.
1. Are there flights that has this "first come first served" policy? Is this policy compatible with the online-seat-booking procedure?
2. Is it rude in these cases to sit next to someone even though you are sitting in your booked/confirmed seat?