Find a set of permanent markers that matches the original upholstery color. Select several colors that are in the range and hold them up to the upholstery to see which ones are the closest match. Search at art stores if you need a wider range of colors.
Test one of the permanent markers on the upholstery by coloring a small bleach stain in an inconspicuous location. Make sure the color matches well. Change colors or blend them together, as necessary, for the best results.
Fill in the remaining bleach spots with the markers. Use each pen against and with the grain of the fiber to ensure it covers both sides. Let it dry thoroughly before using the couch. Most permanent markers dry very quickly. It will feel dry to the touch once the color has set.