When I first joined my Shul, I floated between different Minyanim and didn't feel as though I truly had a set place where I belonged. After a couple of years, I picked the "main" Minyan in the Shul's main sanctuary, and I picked one spot there to Daven. It's a large Shul with several Minyanim, so I was a little surprised, though not entirely shocked, when a friend told me after a few weeks sitting there that I'd displaced an entire family that had been sitting there for three generations. I guess they were just being nice and didn't want to make me feel awkward, but by my sitting in that one spot, this rather large family that typically took up an entire row so that they could sit together, from grandfather through grandson, moved and scattered throughout that section of the Shul. I immediately moved over one row, and I soon noticed that they returned. I was pretty embarrassed, but glad that I was able to rectify the situation.
I then sat in this new seat for about six years without incident. I grew attached to this seat, and I even managed to get it assigned as my High Holy Days seat (usually, seats are reassigned from year to year or chosen through lottery if the seat isn't held by someone the previous year). I was very proud that I had what I could definitively say was my Makom Kavua'.
One day, though, I arrived late, and I discovered someone in my seat. I recognized him as a regular in a different Minyan that I'd previously tried out. I didn't say anything, since I'd been late, and since he probably just didn't know it was my seat, and I just moved over one row. The next week the same thing happened. And the next. And the next. I finally got up the courage to ask him if, like the family I'd inadvertently displaced for a month or so, perhaps I'd been displacing him all this time. He gave me a vague answer suggesting that he preferred that seat when he comes, but he didn't really state outright that it was his, nor for how long he'd had that seat in mind. I had so many questions that I just couldn't get him to answer directly. Did it predate my arrival? How often did he Daven there anyway? He just wouldn't give me a straight answer.
I made a point of trying to get there on time. I noticed that he started arriving early. Eventually he stopped coming (for the most part) and went back to his other Minyan. But every once in a while, he shows up early and takes my seat!
I once asked the rabbi what to do, and he did not support any action that might cause a conflict and advised me to just be on time or let him have it.
Meanwhile, a couple of years ago, someone else showed up in my seat. I recognized him as well, only he didn't even go to my Shul. He was a longtime member of a different Shul, and was even a past president there. I didn't want to say anything, but then he showed up again the next week. I thought, "Here we go again!" I asked him if he had a particular attachment to this seat that I'd been sitting in for going on 8 years. He said it had been his seat for well over a decade, once upon a time. I said that I know he goes to a different Shul, and that I'd appreciate it if he'd let me have it, since I'd been sitting there for so long. He emphasized that he is a member of both Shuls, and that he still considered it to be his seat.
So now I have two people vying for the same seat I've sat in for about a decade. I can't seem to shake either one of them other than by coming extra early and never leaving for a bathroom break. They just seem to go out of their way to snag this seat whenever they are in that Minyan (and they come more frequently than they used to). I wonder: Is there anything in Halachah or common practice that I can bring to their attention (or the rabbi's), or am I just being too attached to my seat?