Extremely Loud and Incredibly Close- parallel stories

wow. The story comes together after reading pages 262-284, the grandfather's account of how the letter saying "i'm sorry" first came to grandmother (page 233) The grandfather talks about how he has been following Oskar and Mr. Black all over the place in order to find out more about his grandson. The story  that the grandpa tells is exactly that which Oskar tells "the renter" (his grandfather) in pages 237-259.  The parallel between these account is empowering and incredible. All along, we find that the grandfather has been around and following Oskar, who has no idea that he even has a grandfather. It snot until the grandfathers letter to his son (Oskar's dad) that we find out all of these things, making the story come together perfectly. This parallel account culminates as they dig up dad's grave, even though Oskar still thinks that the man who has helped him and listened to him all this time, is the renter that his grandmother has been so sneaky about.