A friend of mine (whose children are the same age as mine, only they're older sister / younger brother) was telling me about how her daughter is the discipline shield for her little brother.  Whenever he gets in trouble, M stands in front of C and says "No Mommy!  He's just a baby!"
I couldn't help but think about how different it is in our household.  I'm going to blame it on the older brother / younger sister scenario we have going on... but when ZB gets in trouble, Jav is right there to offer his assistance.  Not to her... to us.
"Mom!  She needs disciplined!  I'll do it if you want me to."
One afternoon in the car, Z got a little lippy (as a pre-toddler girl is apt to do) and I looked at her in the mirror and said "Zailey Belle Hodson!"
Jav said "Mom, you give me permission - I'll slap her."
Wow.  I said "I appreciate your willingness to help out, but do not slap your sister."