Chapter 9-Rumfoord the older cousin?

When Billy Pilgrim is in the hospital in Vermont after the plane crash and his roommate, Rumfoord, is reading articles about the destruction of Dresden he acts kind of like an older cousin. When Rumfoord is reading these articles Billy chimes in and simply says "I was there." Rumfoord does not believe him and says he has echolalia, a disease where the mentally unstable repeat what those around them say. This is like an older cousin because when you are young you always want to hang out with the big kids and do what the big kids do. When you do get to hang with the older kids and you find something you have done that your older cousin cannot you always tell them because it makes you feel cool to do something that kids older than you cannot do. Your cousins usually woud simply say "Yeah whatever!" or "Ok let see it!". This reminds me of Rumfoord because he did not believe Billy was in Dresden and he just tried to ignore him until he found out he really was there.