We all know how important our main characters are, right? Without a protagonist there is no antagonist and vice versa. Often, the protagonist has a best friend-a supporting role.
Now, what about the rest of the cast? Even the tiniest role in a book is a supporting role. A role deemed worthy of award winning possibilities. They must be. There must be a reason for them to be there.
Even in YA, I don't have the parents around just sitting on the couch and watching TV....unless, that's what they do that annoys their teenager so much that she feels the need to go blow up the network station.
In our lives, we tend to have folks that drift in and out without contributing much to our existence other than a new face or a friendly smile. In our writing, those folks do not exist.
My first attempt at a novel, written at the age of twelve or thirteen, had TEN, count them TEN MAIN characters. I hadn't grasped the concept of subtle supporting roles. Beware of this. Do not allow your supporting characters to overpower your main characters, but rather add to them, lift them and push them in a way to move the rest of the plot forward.
How about your supporting roles? Are you staying conscious to keep them relevant and supportive, rather than distracting?