I travelled yesterday in an A320 in CE ex LHR (flight details withheld to protect the, um, guilty). It was a pretty lsat minute booking (booked a few days before), and when choosing seating, all of CE was unavailable except for row 1 which was completely empty. That's fine, I like the bulkhead, so chose 1A, and hoped 1C would stay empty (as it often is when Golds have chosen 1A).

When I got on the plane, a woman was in 1A (my seat) and a man in 1C. I said to the woman "excuse me, I think you're in my seat". She started to apologise and get up to move, but the man asked if I could sit in row 2 as he and his partner could not find a seat together. I have no problem with asking, but I actually wanted the bulkhead row, and it transpired the woman's correct seat was in fact 2C (not a million miles away), and the man appeared to find it difficult to take no for an answer. Eventually I said "well, this is the better seat, so why don't you ask whoever is in 2A behind you to swap with you - I'm sure they'd be glad of the slightly better seat and you can sit next to your partner". At this point the woman moved back a row, and the man continued to sit in 1C quietly fuming.

Once the door closed, after some conversation between the two in a language I don't understand, the man got up and went to sit in 2A (behind me), still evidently cross. Whatever the language was had a word used quite a lot that sounds a lot like "ducking". And the charming individual decided to put his knees into the back of the seat regularly throughout the flight.

I am 90% sure that actually both were originally assigned to row 2 (2A and 2C), and they just thought they would like the bulkhead row.