How did this herd come to be? Thats a story involving to very unlikely partners.
Noir had come to hate flowers. Whenever he saw them he couldn't help but stomp on them, getting teased by a younger stallions who was much larger. When this stallion stomped around the grumpy, older usdia, he would faint.
Starlet was a playful mare, that enjoyed life. She could be said to be the complete opposite of Noir. When she had happen on Noir and the larger stallion, thinking he was being attack, she stepped up and stepped in against the 'bully'. And in the end it turned out the larger stallion was some what of a wussy flower lover, once confronted he turned and ran as fast as he could. Leaving Noir some what thankful.
From then on, Starlet would check in on the grumpy Usdia stallion. When they were together one day, Starlet mentioned wanting a home away from home... Noir mumbled something about ruling herd.... Needless to say Starlet annoyed him enough to get co-alpha status.
There is a benefit to have two polar opposites. Noir being more aggressive, and a warrior type leader. Starlet is more passive, and diplomatic. They would have to work together, and find a common ground, which would usually then result in the best interest of the herd.