The Last Book In The Universe

In this dystopian world, books are replaced by mind-probes, unusable by narrator Spaz 15ish, because of the epilepsy he is named for. After the "Big Shake" apocalyptic earthquake fells "backtime" skyscrapers and civilization, Normals survive in the concrete-smog grey Urb by working for "cut your red" killer gang bosses. Sent to rob Ryter, the boy instead gains a mentor, "gummy" old mostly toothless writer, who guides their quest by the sun. Far away, where Spaz was banished for his illness, beloved unrelated younger sister Bean is dying.