free writing topic to think about

On page 97 Foer writes:

"I asked, 'Are you sure you didn't know a Thomas Schell?' She said, 'I didn't know Thomas Schell,' but for some reason I still didn't believe her. 'Maybe you know someone else with the first name Thomas? Or someone else with the last name Schell?' 'No.' I kept thinking there was something she wasn't telling me. I showed her the little envelope again."

In this quote Oskar refuses to believe that Abby Black had nothing to do with his dad for some "reason". Even though Oskar has over 200 people on his list with the last name Black he still tries so hard to find a connection with Abby even though she is only the second person he's met. Oskar also worked so hard just to talk to the first man with the last name of Black even though it was highly unlikely he had something to do with the key or his dad. Is how Oskar approached the first two people childhood curiosity or something more? Why is Oskar so persistent in trying to find answers about his Dad through them and why additionally does he go on to talk to them at a personal level?