In the novel, The Adoration of Jenna Fox, there are many areas and themes that challenge ethical and moral considerations. There are scientific considerations that walk a very thin line between right and wrong. This may also be indicated in the shading of the pages. There is also the consideration of self identity. For the new Jenna, trying to cope with the former memories and the new life lead her down some morally gray areas.
Also, they are a symbol of the 10% of her brain that they saved, 10% of the book is Gray Pages