Answer:
I spend most of my day eating white. When I am quick enough I get rewarded with fruit and something blue. In a dark room with blue walls I run from the ghosts that roam the halls
With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?
I have cities with no people forests with no trees and oceans with no water.
I am pronounced as one letter written with three. I come in blue black brown or grey. Reverse me and I read the same either way.
I have two bodies joined together as one. When standing still I run and run.
No matter how little or how much you use me, you change me every month.