All three of my horses are completely different when it comes to how they interact with other horses. It is kind of funny; I have the social butterfly, the loner, and the easygoing friend-with-everyone horse. LOL!
Reva is a social butterfly. She loves people, she loves other horses, and would probably enjoy more of a social life, if only I had the right horses to turn her out with. Right now, everyone is turned out alone, with smaller
Dreamy never learned how to play with others in kindergarten. She was (probably) not turned out much as a 2 and 3 year old racehorse, and then she became a baby making machine, only turned out with her foal. So she has never learned the manners appropriate to having a social life. She kicks the living snot out of everyone I have tried to turn her out with! Dreamy has always been a bit of a loner, whether that is her natural personality or just has become her personality due to her lack of interactions. The only horse Dreamy has ever really taken a shine to is McKeever, my friend Shelly's gelding. McKeever has his own bad manners at times, having been gelded late in life. However the two of them are in love, and we often refer to them as an old married couple. They have traveled many, many miles together in the horse trailer and stabled together at many shows and events. They actually get along great, and I bet they could even be turned out together if the situation ever presented itself.
Sparky has been turned out with many horses over the past (almost) 19 years I have owned her. She gets along with everyone and she hates being left alone. She has been at the bottom of the pecking order, the top, and in between. Her best buddy was my grandfather's Standardbred Volo. They were seriously two-peas-in-a-pod. The best turnout for her was when I briefly boarded her back at the farm where she was born; she was turned out with her mother and full sister. That was a pretty neat experience, because based on the way she acted with her dam (also called Sparky...so we called them "Sparky Sr." and "Sparky Jr." LOL!) it was clear that they remembered each other. At almost 30 years old, Sparky has earned the right to her own space. I think she enjoys having her own paddock/pasture and loves to stand close to Reva with a fence between them.