This is what I mean by friends with benefits – your characterizations benefit by having a group of protagonists and antagonists. As a writer, you need to look at your ‘cast’ and make sure they can work as a team in your narrative.
The love of family and the admiration of friends is much more important than wealth and privilege.
As a writer, my characterizations can be as simple or complex as I want them to be. But no woman is an island. When constructing a character, you have to consider her friends and family. The relationships that your character treasures and nurtures, or allows to dwindle, can tell you much about a character as the way she fidgets in the presence of chocolate or sharpens her throwing knives when she is relaxing.
My mother says ‘Water finds its own level’, which is her way of saying that you generally find friends of a similar class sharing similar interests. This happens at family gatherings as well; you will tend to hang out with the relatives that you share a history with, rather than the obscure second cousins or frail great aunts who smell of lavender. (Unless you’re like me and hang out with everybody to get updates on the family news and gossip.)
So, what does this kind of situation mean for your character? If you paint with broad strokes, it means you are unlikely to find a saint living in a den of iniquity, or a true sinner making sacrifices for the sake of a pure soul. If you aim to be more subtle, it means finding a group of family and friends that help colour in the details of each others’ characterization. Who the best friend is can tell you a lot about a character. Look at Holmes and Watson for an example … we know that Holmes must find something in Doctor Watson that appeals to him. Watson is intellectual – though not a genius – and a superior medical officer and crack shot, but such men are not rare. However, Watson is well aware of his limitations and doesn’t have a jealous or envious nature … and they are rarer qualities. But what makes them friends is a shared sense of black humour, and the sunny, steadfast nature of Watson being able to anchor the more emotional and mental extremes of Holmes.
Another example would be the Pevensie family from the Narnia books. Each of the four children stood for a certain trait: Bravery, Kindness, Deceit/Justice and Steadfastness. As a family, each sibling had virtues and flaws that balanced with the three other siblings’ flaws and virtues (it does get treacly thick at times). Or you could categorize them as Brains, Heart, Action and Faith. It doesn’t matter how you dice it up, but the siblings were a cohesive group and their individual characterizations were interdependent on the group.
My Steampunk protagonist has aspects of her personality revealed by the friends and enemies she makes. She is drawn to scientists and academics, because of her own obsession with the biological sciences. Her best friend is her lab assistant, because they work well together as a team. This is my own take on a Holmes and Watson style of relationship.