I seriously just wanted to draw a bunch of ninjas. I was about to do the Ninja Turtles, but then opted to do Daredevil and Black Widow. I was going to draw the old school Frank Miller Black Widow, but then saw the Iron Man 2 trailer and I had to draw the new Widow.
The color scheme is an homage to Daredevil issue #189. One of the greatest comic covers ever!