A little window into the differences between my kids

We took the kids to the book fair at their school tonight. My parents took them and then I met them there. It was also a "family fun night" where the kids could do crafts. I had a short conversation with each of the kids that points out a couple of their personality differences:

Me: Z, finish up your last craft and then let's walk through the book fair and I'll buy you a book.

Z: But Grandma already bought us each a book...

Me: That's okay, I'll still buy you another.

Then I went to another table to talk to A:

Me: A, finish up your last craft and then let's walk through the book fair and I'll buy you a book.

A: But Gran-- hmm. Okay, Daddy.