The main function of the narrative illustrator is to represent, interpret, and heighten the meaning of a selected passage of text (in a complementary way) by means of pictures, with the aim of contributing to the reader's appreciation of the narrative. This usually involves consideration of the setting of place and time and the nature and action of the characters who take part in the story. Pictorial narratives may, of course, dispense with words. My talk today will mainly touch on various elements of narrative illustration and what we often have to consider when we are illustrating texts.
Ganked from http://www.fulltable.com/vts/n/ni/n.htm
Jus' doing a bit of reading.