Originally Posted by Thysk

Something similar happened to me on my UA SCL-IAH flight. 2-3-2 config in y+, I had a window seat and seat next to me was empty when taking off. After dinner, I feel asleep (redeye flight) (with the seat next to me still empty). Low and behold 2 hours later, I wake up and THERE IS ACTUALLY SOMEONE SITTING/SLEEPING NEXT TO ME.
I was too drowsy and dumbfounded to do anything (and eventually fell back asleep), plus I couldn't find the "ring FA button" (apparently they're on the screen, not next to the overhead nozzles), but next time I sure as hell will voice my displeasure, plus boot the pax out of the supposedly empty seat.