At first sight, this seems the most unlikely of pairings, and then, when you get into their dynamics, it becomes completely logica. Both from pureblood families (and I love their easy gossip - the story about the Tinwitty-Peppercorns is priceless), but have issues with brothers, chosen ones, real ones, hated-yet-loved ones. And both are more or less outcasts.
You give us such a believable picture of these two.
I can hardly remember why now. Probably for a laugh. Everything was a laugh then. Everything isn't so funny now."
"Things weren't funny then, you were too young to realize it." Great lines.