@Mary Maybe the urgency of the position/person the heir is meant to succeed is directly proportional to the swiftness of their promotion? Usually, the heir has to do it like every other noble but when the noble family senses chaos and anarchy brewing, they make the heir into a Marquis directly.
I have a biopunk nation. One of their most commonly used body modifications are 9 large, fluffy tails so basically nine-tailed humans. What possible benefits could these tails offer?