When we met it was just an outline. She got it colored in while we were together. The red one was her and the blue one was me. The chaplain who did her service suggested an even cooler meaning for it. He said that the red represents the solar and the electrical, and the blue represents the lunar and the magnetic, and together they represent the two kinds of energy that flow through the body.
I'm going to get a cleaned up, nicer version of this, with three fireflies flying around in it. Three for three kids. :-)