Oh, what a great take on the topic. My brother and I are 8 years apart in age, so I never really experienced this (I was more a caretaker than an older sister), but we'll joke around about the fact my mother clearly loves him more, or that I'm more artistic, or other silly things siblings "fight" about that amount to nothing in the end. And we do it as a way of saying, "we never got to fight over fun things as kids, so we'll mock that as adults to show that we love each other." It's fun :)