When creating a character a good place to begin is to create backstory. Include the basics such as complete name (if named after someone or if name has significance to family), age (incidents at birth, toddlerhood, teen years), occupation (something he enjoys or hates?), marital status (looking? Engaged? Committed? Divorced?) and residence (city, state, country, type of dwelling, owned or rented or leased, living with someone and relationship to others in the house).
Wow! That’s a lot of information, most of which you will never use. As detailed at that is, however, it will not create the type of complex character that interests readers. Complexity often comes through a weaving together of villain and protagonist, a melding of relationships and story.
We might meet the villain first, see him doing something rather ordinary such as cooking a meal or carrying a load of lumber at work. He might be a grouch or overly pleasant, a sycophant or misogynist. Now we don’t like him as much. In fact, he is grating on our sensibilities.
Your task is to have your character come up against the villain for the first time. Is there friction? Or do they bond over drinks? Remember that there must be tension, so does something happen that angers the villain or terrifies the protagonist? Make it interesting so that your character becomes a complex individual.
Have fun with this one.