My friend Sandy asked me what flair pens are. They are fine point water soluble pens that you can get at any office supply store. I get mine at Staples. When I'm ready to add color to a drawing but I don't have my watercolors with me, flair pens are an easy way to "paint" on the go.
Adding water will make the color of the flair pen bleed and blend like watercolor while retaining some of the line quality.