When I feed everyone we follow a routine, and I feed each horse in the same order every single time. Mostly this follows their established "pecking order," but sometimes it just depends on who is more excited about being fed. In the group that Harmony and Buffy live in, I always fed Buffy second and Harmony third in the order. Feeding time is really a non-event around here. I use feedbags, which I think are the greatest invention since sliced bread, so the horses learn quickly that they can't steal and no one can steal from them. It works perfectly as everyone is quiet and orderly, everyone gets all of their food and ONLY their food, you know they got their supplements, you can feed soaked feed in the bags and life is good.
A few days ago I was feeding the horses in the pasture where these two girls live. Harmony does this thing where she very quietly and slowly walks around while waiting for her feedbag. She had always done this and the others don't pay any attention to it. I don't know if she walked closer to Buffy than normal or what, but one day Buffy flattened her ears back and got the whole "snake" move going with her head and neck. Well, this really rubbed Harmony the wrong way as she spun around and stood with her butt to Buffy with her ears flattened on her head.
No one budged, they were about 10 feet away from each other doing their best attempts at posturing. To my surprise Buffy backed down first. The ears came up and she was a happy mare again. So Harmony swung around and she was a happy mare again, too. And she was closer to me than Buffy at this point so she was fed before Buffy. And has been ever since! They both now pin their ears at each other at feeding time, but that is as fussy as they get. Then they proceed to eat almost nose to nose with each other, and then wander off to graze together.