This is usually subconscious and relies on word sounds.
For example, if you want to associate a character with energy and activity, you’d want to use a firm and short name.
If those guys were named John or Mike, we might feel confused and disorientated.
For example, my Agent Black is also known as the Manhattan Mangler.
If I gave you only one of those, you would probably reach a different conclusion about how just, unique and proper he is.
Authors sometimes complicate this by using the same letter to start character names, using similar-looking or similar-sounding names.
We will keep John and Hideyuki apart in our minds, but maybe not Clinton and Cliff (or Kevin).
The problem with the worship of the alpha male starts with the current fad of explaining male and female sexual behaviors via evolutionary psychology and involves two disparite beliefs.
The first belief is the modern narrative of sexual behavior in men and women.
Obviously, most writers have to be more subtle than that.
“Neville Longbottom” is a great example of a name that suggests a trait without being too ridiculous.
As a rule of thumb, once you have used a given letter to start a character’s name, you can’t use it again.
If your work is long enough that you name 15 characters, then you can start sharing the letters of minor characters who appear in completely different parts of the book.
Character names serve several important roles, like differentiating characters and evoking an emotional response from readers.