We have two girls living in the house... one 17 an the other 15. At first it was like two cats that meet in an alley and want to prove the other is bigger and badder. Then they started hanging around and sharing things. That lasted for about three seconds. Then they are back to bickering and seeing which can trump the other in a verbal battle.
On the parental side we can't win. If you say one thing to one the other thinks you don't love her. If you don't say anything at all they don't feel you are standing up for them.
It's almost like a competition, only I'm not sure where the finish line is and what the prize is at the end of their race.
But one did ask me tonight, "When do we start therapy?"