In the hopes of reviving this lovely thread, and getting us back on track:

A few years back, I was on an early morning SAT-IAH-??? and got on board to find a guy in my aisle seat with the middle open. I politely said, "I think that's my seat" and waited for him to move over. Instead, he looked me up and down and said, "You don't look too big, you won't mind sitting there." He nodded towards the middle seat and swung his legs out into the aisle so I could squeeze past.

Now, if the guy had been polite about it instead of just demanding that I take the middle, I'd probably have been ok with it. Sure, I was exhausted because I was only on the flight because of MX issues and reroute problems, but the guy was probably 30+ years my senior (I was in my mid-20s), it's a short flight, and I am a pretty skinny guy. (I'm tall, but this was in an E+ row so nbd either way.)

However, his attitude and especially the way he just demanded what would be best irked me, and I said, "No thank you, sir, that is my seat." He harrumphed and snorted and slowly and irritably moved into the middle seat while I took the aisle.

What followed was a 45 minute flight that this guy was determined to make miserable for me for not switching with him. He stuck his knees into my space, leaned across the armrest, tried to dig his elbows into my arms, and generally tried to encroach as much as possible. However, two can play at that game, and I am not beneath giving as good as I get. As I mentioned, I'm skinny = angular frame = bony, so if we end up pushing back and forth you'll probably end up in more discomfort than I will.

His elbow came into my arm, so I angled my elbow to push into his. His leg came over, out went my knee. His shoulder leaned onto my side, I pushed right back. The entire time I had my head slumped forward on my chest with my eyes closed because I was still really tired, but I could hear him grunting with exasperation. Eventually after 20 minutes or so of this (with me enjoying the fight, since it was clear who was "winning" and also because I was a bit of a young punk), he actually called me out for pushing into him. I calmly pointed out the dividing line between the seats and said that I was staying completely within my seat's boundaries, and if he did the same we wouldn't come into any contact; then I returned to my slumped forward position.

He tried a few more times to angle behind/into my side, and each time I met him (fully on my side of the armrest) with far bonier appendages. Eventually he gave up somewhere around final descent into Houston and just sat there. When we landed, I grabbed my backpack and never looked back but could still hear him muttering behind me.