I have to admit here that the book of Job is pretty much beyond my comprehension. So I did a lot of swirls on these pages, they are easy and mindless as my mind struggled to see the points of Job's story.
I think they also represent my confusion.
These were all done with a fine purple ball point pen outline and colored with watercolors. The pages were not prepped in any way. To get the dark areas you can do layers or a fairly dry brush. Another option is to go over the watercolor with colored pencils. You can also see that the shading of the swirls is done with the pen before adding the watercolor.
Highlighted verses are done in watercolor also with a silver or gold metallic pen for the outlines.