My mare's different. Animal dominance and social hierarchy interests me, so I've watch her for a long time; she doesn't have any buddy horse on property but plenty of horse neighbors in sight and in earshot, she doesn't seem fond of the pig I paired with her.
She is a calm bum to begin with, though not a dead head--- she has an explosion once a year (something like running into the gate, rearing, by herself), and ordinarily doesn't fuss unless it's estrus time in which case she decides to ignore recall sometimes. Not the kind of horse that would spook and bolt, she can be surprised, but rarely spooks, when she does she shies away/gives a half-step/quickens briefly. Fireworks are nothing to her, she was already police-trained and doesn't care for a gunshot yet expects some treats when one goes off. However, she does get upset when the neighbor horses do. For the 4th of July, I have to work her out substantially in the morning and make sure everything is secure; she usually spends her time pacing by the pasture gate in her paddock and might answer any frantic neighs from the neighbors. She's alert and paying sharp attention, nothing more.
So when I put her out in pasture, I like to watch when the neighbor's horses are close to the fence. Usually, she gravitates to one set of paddocks by the fence because this group of horses has little change in its herd and they usually stay in their stall/paddock combos except for turn-out for a few hours a day. That's her adopted herd, sometimes in high spirits she will gallop out to them, slide-stop into the corner, wait for a moment as they trot out to greet, and then she grazes by that fenceline, drifting away toward the far end over the course of an hour. She demands to be the queen, silently. Another herd of horses is let out by the fenceline from a lesson/training stable that constantly changes members, so usually I don't see her interested in these horses if her adopted herd is available. The standard is that when these horses are out, she might prance up to the fence in a showy manner if it is a big herd or a mare is there, or take her time walking up, then she waits for them to come to her. They usually come running. She sniffs noses, squeals and stomps, then walks off to the farthest end of the pasture and grazes, always with an eye on that herd. If they spook and run, she turns toward them and signals with her tail, or might neigh, and return to grazing. She has every herd wrapped around her hoof, and it's interesting to see how she could do that with so little work. It's all presence. When I take her out of the pasture, the boarder herd goes crazy and they run around frantically neighing. She neighs back once or twice, as if to say, "QUIET! I'm right here!" then really doesn't give much a care for them.
It's a spectacle to see the boarders try to catch their horses when my mare is out near them, because they REFUSE to leave her. They have to get several people out to corner the horses or ride up with another horse to lead them out.
My mare usually comes on command, but lately with the new mare in her favorite herd, she see me and goes to them, looks, and then comes to me. Just making sure her lot is okay and reassuring them before leaving, I think.