Do you remember how Tony was talking at the beginning, as if to the audience? At the end he starts talking again, but it's revealed that he's actually been talking to Bruce Banner (Hulk) in an office, as if to a psychiatrist. But Bruce has fallen asleep during the story. When he wakes up he half-heartedly protests that he's not really that kind of doctor, but Tony either doesn't care or doesn't mind as he launches into his story again from the beginning.