Sometimes being a brother is even better than being a superhero. - Marc Brown

I'm 5 years older than my younger sister.  
While it doesn't seem like a lot of years - it truly is.
The age difference between 10 and 5 is tremendous.
15 and 10; 20 and 15 - equally so.
By the time you're 30 and 25 it pretty much equals out and you're both "grownups" on the same page.

But I was never mean to my sister.
I might have played a prank...but I never set out to hurt her feelings, or make her feel badly about herself.  Had I known more of the people that weren't nice to her when she was younger, I'd have "kicked their asses".  I had no one to protect me, and I would've definitely protected her. 

I've never, ever laid a hand on my sister - ever.  (Trust me, there have been times when I've wanted to, but I'd never done it....)

So I don't understand the dynamic between my son and my daughter.
He's just so mean to her.

He doesn't get that he is her everything...her best friend, actually.  And that she hangs for his approval on everything. The quote I chose for my title is almost verbatim of what I try to explain to him - about how important he is to her.  I can't tell if he doesn't understand --or maybe he does get it and just doesn't care - which makes his unkindness to her that much worse.

Don't get me wrong - there are some days when they are frick and frack.  Best buddies and life couldn't be better.  But lately, it just seems like he's all about tearing her down and making her doubt herself.  He's just being mean...and that, I don't understand at all.

Of course,  I never had a brother -so maybe that's just what they do.

Anyone...?  Anyone?