[Senkusha]

A Story Arc in which two characters or groups slowly, and involuntarily, swap their positions in life. These positions are usually social (who has high-status, who is popular), economic (who is rich), and most of all, moral ? who is decent and who is a ruthless bastard. The swapping often leads to escalation ? the new poor person is poorer than the old one was, or the new amoral one is much nastier than the old one was.
The pathos from the Hourglass Plot comes from how neither character learns from the situation ? they act just the same to each other as they did before, but with roles reversed. Particularly cruel shows will create an infinite-loop Hourglass Plot, where two hostile characters keep swapping positions and treating each other as badly as ever. In rare cases, such plots will involve the characters barely interacting with each other... a pure comparison of one person's rise to another person's fall. 

I saw this on a Tropes website while researching more Magical Girl anime titles, and this popped out at me.  And, like, OMG, it's kinda true!

Sorry but you are not allowed to view spoiler contents.

What do you think about this. I never thought about this plot point before.  And, does this actually happen in real life too?