I found a few photo references for each character, and just started laying down basic shapes in Freehand. I challenged myself to keep the shapes as primitive as possible, to see if I could still render a recognizable likeness. I kept the images very formal, so the face structures are completely symmetrical.
At first, Lisbeth's eyes and nose ring were round, but they stood out as the only curved shapes, so I went back and replaced them with flat shapes later. Restricting the shapes this way seemed to work - it kept the style cohesive.
I kept the colors limited, and allowed only one level of highlight and shadow for each colored surface. The backgrounds were pulled from the eye colors.
|Detail - before and after grunge.|
When the images were finished, I pulled the vector shapes into Photoshop (keeping them as Smart Objects, so they could be resized - even larger - without any quality loss) and added some texture. The grunge layers were free high-res files that I found online. The layer modes were set to Multiply. Lisbeth's texture looked perfect as it was (it had a nice natural gradation - darker at the edges and lighter in the middle), but Mikael's needed some erasing in the center, so as not to obscure his face too much.
And that's it. Here are the final pieces:
UPDATE: It looks like the style is sticking around. I've launched a mini-site showcasing these illustrations: