And he hates the Habsburgs too.Remember that episode when the emperor ditched him right before Charles was supposed to be crowned?Even if that event isn't butterflied,Charles is in a position to make sure his grandchildren remaining the kings of France by marrying his daughter to his heir.I don't think it would be realistic for Charles to let the throne slip out of his line.Realistically,the guy would try any method possible to make sure France remained with his line,especially if it's going to someone he hated.Marrying Mary to this guy and having their children take over the throne is the next best thing.