Nate has been just desperate to play with Jack, trying to instigate games and ask him questions. It's painful to watch because I so want to encourage his attempts to play nicely with Jack, but Jack's just too young to understand what Nate wants of him.
Sometimes, though, it all comes together. Jack is finally of service to Nate.
My favorite part is the end where it looks like Jack has run out of patience and grabbed a nearby stick to brain Nate with. In reality he just handed the stick to him; a loyal servant to the end.