In the Harry Potter series, J. K. Rowling repeatedly uses a very effective technique: turning a character, initially introduced as part of the background, into a foreground character. This happens with the characters of Gilderoy Lockhart, Viktor Krum and Sirius Black for instance. In fact she uses the technique so frequently (with even minor characters like Mr. Ollivander and Stan Shunpike) that the background starts to empty out.
This is rather annoying because the narrative suggests and promises a very large world — comparable in scope and complexity to the Lord of the Rings world say — but delivers a very small world in which everybody knows everybody. You are promised an epic story about the fate of human civilization, but get what feels like the story of a small town. Characters end up influencing each other’s lives a little too frequently, given the apparent size of the canvas.
We are used to big worlds that act big and small worlds that act small. We are not used to big worlds that act small.
Which is a problem, because that’s the sort of world we now live in. Our world is turning into Rowling’s world.