Sibling Rivalry...with an only child

I experienced something with Aaron this morning that I never imagined I would have...him being an only child and all.

Aaron noticed some pen marks on the sheets on my bed and asked what happened. I said, "It looks like you drew on my bed." He responded, without missing a beat, "No, Tanner did it."

Tanner is the babysitter's son...who has never been to our house...ever.

I'm interested to find out how many more conversations I'll have over the years that I never thought I would have with an only child.