I'm inspired by drakkar's thread Reminder - Wednesday, October 21 from October 2009. (I hadn't heard of LTROI back then and wouldn't for another year.) I can't go into that thread, of course, and add my comments in with theirs. drakkar talks here about today being the day Eli and Oskar first met. But I can write this thread in parallel.
Interesting point they make that at the end of the story we don't know that Eli & Oskar take the train all the way to Karlstad. We only know what they were on the train to Karlstad.
Ever notice how the chapter in the novel for this day begins and ends with a similar theme? At the start we have Oskar's mom saying "You are not allowed to go past the yard now, as long as this... Until they've caught him." / (Ger.) "Du gehst nicht mehr in Hof, solange das... Bis sie ihn verhaftet haben." And near the end we have Eli saying "I can't be friends with you. Just so you know." / (Ger.) "Wir können keine Freunde werden. Nur dass du es weißt." Each are constraining Oskar. Each is providing a definition on what is going to be allowed. And is each trying to protect him? Or is that a stretch?
The middle of the chapter is loaded with Tommy. I've wondered often whether if Oskar is to be a fictionalization of 12 year old JAL that maybe then Tommy is a further fictonalizaton of some aspects of JAL from when he was then four years older.