After 50 chapters about Kaguya and how she planned on using Madara, because she was foiled by her two sons, were gonna get the sage's brother. He's gonna be the final villain.
What's messed up about how Rowling did it, was that she planned those pairings since the beginning. However HG got next to no development and RH didn't seem to match up at all. Yeah we had the classic 'boy is mean to girl he likes', but they don't seem compatible at all. I know opposites attract, but they always seemed to put the other down and argue with each other and I rarely saw them interact positively with one another, unless it was to help Harry. Though, that could be because I only saw the movies.