Why is it always the black marker??

So this morning I was hanging with Noah in the living room while he was building with his legos. Cooper was supposed to be watching The Princess and the Frog...

A quiet 2 1/2 year old is never a good sign...

Cooper got Noah's markers and created his own artwork...on the wall and his body.

Thank goodness for the magic eraser! It took the marker right off the wall. The same could not be said for his body. A bath and lots of soap later, he now has green marks all over his body and hands. Why is it always the black marker that he wants??