I nearly got into a fight on the flight home. My seat was on the aisle in the exit row. They closed the door, and I had one of about four empty seats next to me. But then a late straggler, a slightly flabby middle-aged gentleman, decided that he wanted to switch off his middle seat, said something to the flight attendant, then walked over and sat next to me. He was an elbower. He began claiming his territory by shoving my arm off the armrest, then applied constant hard pressure to my arm and ribs with his arm, which was already draped over the armrest onto my seat. I'd already taken melatonin and dramamine, I've got earplugs, headphones, an eyemask, and a blanket in or on me - I was just trying to go to sleep. After a couple of minutes he announced "Guy, I don't have any problem sharing the armrest, but c'mon." I said that obviously he DID have a problem sharing the armrest, because he's shoved my arm off it. Then I cover myself back up for napping, but the brief exchange gave King Ahole the opportunity to encroach even further into my seat. The petty stupidity continued for another couple of minutes, until he's elbowing my ribs as hard as he can. I was restraining the urge to haul off and slug him, because I didn't feel like getting arrested when we landed.
Instead, I rang the call button. The attendant came over to see what's up. I explained that unfortunately, my neighbor was elbowing me hard, shoving me, and trying to create an altercation while I was lying there, trying to sleep. He give what I assume was his patented King Ahole chortle and announced that "he's just trying to watch TV and change the channels" and that I was blocking him. But he did it in his joyless laughing voice that was supposed to get people around him laughing at me. The attendant found another seat, further back but on the aisle, and said that we need to not be sitting next to each other. King Ahole just sat there for a minute with the "I'm not budging" body language, and suggested that I get up and move. I finally announced that I'm not moving, that I have a boarding pass for the exit row, and that he can't produce a boarding pass for the seat he's in so he'd better just move. He grumbled that "this is where they told me to sit," then got up eeeeextra slowly, glared at me, and moved.
No further trouble, but I kept wondering whether he'd confront me at the luggage claim. I was running through what I'd do if he tried to menace me, deciding to say something like "I'm sorry you were uncomfortable on the flight" and then ignoring him. However, his type wasn't actually going to do something in public. Problem solved.