Room is a state of mind
The story of Room is one of escape, of breaking past confinement to reach freedom. By the chapter 'After,' it may seem that we have reached that point, as Ma and Jack have broken out of Room, but still they are not truly free. One of the first things that constrains Ma and Jack still is their weakened immune systems, due to being totally isolated from the outside world and outside illnesses. This impacts Ma and Jack in slightly different ways. Ma knows and understands the situation and seems to consider more an inconvenience than anything. Jack, on the other hand, has been raised to be pretty much terrified of germs, and early on things the scrape on his knee and his dog-bitten finger are going to be the death of him. Even though Jack has left Room, he still brings it with him. For example, his vocabulary. Even though Jack is a remarkably literate five-year-old, the outside world still has an impossible array of things he does not have words for, so he tries to describe the...