Map out a set of characters for your piece so you can play with who your characters will meet, love, hate, rescue, or fight.
Write the full name of your main character in the middle of the page. Add in any nicknames or pet names they have.
Insert all the people in the main character's life around the name in the center and connect them to the protagonist with bold lines. Include names and details for family, friends, work colleagues, neighbors, lovers, and such.
Add people who the main character doesn't know but who might play a part in the story. Don't connect them to the main character just yet. Just come up with a supporting cast.
Draw connections between the other characters but leave your main character out of it for now. Try color-coding them so you know which connections your main character knows and which they are in the dark about.
Identify potential enemies among the characters in these groups. Underline the characters with potential for evil in a different color so you can find them easily.
As you begin to define the relationship your main character has to the rest of the cast, consider writing it down along the lines you've drawn. As the map develops, you may begin to get a much more complete and complex picture of your main character.And the plot of your novel will begin to reveal itself as you find possibilities for connections and further development.