The Golden Mean is a balance of good and evil, bad and fair, light and darkness. When it comes to character virtue, the definition of The Golden Mean is this:
A preferred balance between too much of a virtue, and not enough of a virtue.
When it comes to loyalty there are different phases. Too little, The Golden Mean, and too much. An example of a character with too little loyalty is the hyenas from the lion king.
The hyenas from lion king have too little loyalty because they never listen to scar enough, who is their leader. They show that having little loyalty means you don't listen, and defy higher power.
The character that has too much loyalty is members of the Charles Manson cult.
The Charles Manson cult is the perfect example of people with too much loyalty because they were told to kill other humans in cold blood because some crazy hippie with a Gandalf beard told them to. They didn't measure the consequences, they put way too much loyalty into Manson, and they payed the price.
The Golden Mean of loyalty is Samwise Gamgee.
Samwise shows the Golden Mean of loyalty because he shows loyalty towards frodo without being too attached but at the same time being committed to him enough to push him through to the end. He showed perseverance when accompanying his friend and stayed loyal to save him from certain death.