It's easier to understand the child if you look at the parent, and Harry's dad, Will, seems more feckless than most. He's grieving too, if he'd only admit it, but seems determined to deal with his loss by himself. Mostly, it seems, by disappearing off to work, leaving Harry with a string of au pairs.
Despite Will's insistence that it's none of her business, Holly's sense of responsibility towards Harry means that she can't just walk away. But when professional detachment turns into emotional investment, Holly begins to worry; is this just about Harry? Or should be taking a closer look at herself?