on Fiction University:
No character exists in a vacuum. They are surrounded by friends, enemies, neighbors, coworkers, and a crowd of others. If you put a little work into their tangled web of relationships, it pays off in developing your character, deepening your story, and enriching your world.
Below are the six crucial types of character relationships. Your main character should have at least one of these. Preferably one of each.
As you read through these, think about your main character and this other person. Imagine that you are interviewing your character. Write down the answers. You may be amazed at the wealth of story ideas you uncover.