Those 2

It is fun to see the relationships between my kids change and grow.  As an infant and baby, Lilly was in love with her big brother James.  As a toddler, her wild side is developing, and so is her love for William.  She still loves James lots, but he is her protector.  I can ask him to keep an eye on her and trust that he will.  I would never ask William to keep an eye on her because I'd find the 2 of them pouring water all over the kitchen, or something equally destructive. 

William is her partner in crime.

Here they are screaming together.  They crack each other up.  They egg each other on.  They are often 2 of a kind.  
They wrestle.  I mean really wrestle.  William will have her in a head lock and she doesn't even care.  She just keeps laughing.
She calls him Dee-ha, or Bubba.  Bubba was actually her first word.  It is her name for either brother, and they are her most favorite people.  William knows how to make her laugh better than anyone else.  He genuinely likes her company, and she adores his.
For all his rough housing with her, and the mischief they get into together (already!) their love for each other is very tender.  If Lilly is crying and upset, William runs to her saying, "it's OK Lilly.  Bubba's here.  Bubba's here."  And if William is upset, Lilly does this sympathy moaning cry right along with him.  Then she will give him a pat-pat on the back or some of her love: laying her head on his shoulder.  It is very sweet.

Those 2.  I can't get enough of them.  

(Well, except for the joint screaming.  Then my head spins.)