I really dig this techhnique where you use different color pens to help highlight different things.
if I recall, it started out as a happy accident one day when I ran out of India-Ink and used ballpoint until acquiring more. Then it morphed into using ballpoint like a pencil, and for filler grey-tones etc. I wish my blacks were bolder sometimes in these old Journal drawings.
Oh~ and~ just so ya know: the blueish tint is a result of using diluted white acrylic paint as a wash for the submersed areas ;~j