The stitch for week 2 of TAST was the buttonhole stitch. I used three threads on the smaller stitch and two on the larger one. The three-thread stitch isn't quite straight on the bottom, so I think using only two threads is better for the buttonhole stitch on this fabric.
And as for what these stitches are going to become? Everyone was right - it's a color wheel! I can't wait to see it progress. It's going to be awesome!