There was one gelding that was brought in from pasture that was tough. He was four years old. Had been halter broke at two. Had a few weeks of riding at three. That was the norm at that ranch. Usually worked well.
This one came in breathing fire. Charge anyone who came near the corral. We thought he might have gotten into something toxic, maybe had been fevered and got brain damage. Maybe taken a blow to his head. But, we thought we'd give him a shot at life.
We roped his front legs and slowly pulled him to a stop. He was, um... angry. Then we roped him around the neck. We pulled him over, restrained his legs, and threw a tarp on him. Then waited.
After a bit, when his breathing had calmed and his muscles relaxed, we haltered him and let him up.
He was a different horse. Still flinched when touched for a couple days. Tucked his tail when saddled and for the first few rides. We rode him in a D-ring snaffle, got him going with neck reining, graduated him to a medium port curb (that was right for his mouth).
He became a very good cow horse. Really excelled at sorting and was decent for roping and doctoring.