David vs. Graham
It seemed to me that Graham actually was 1) a good 5-10 years younger than David, 2) much better educated, 3) most likely from a family that valued culture, and had the money and education to appreciate it. David seemed like he was just a working-class guy, who got involved in a good scam, because he had a golden tongue. I think that's why there was an underlying current of tension between them. It's like David knew that Graham could still turn into an honest man, someday, while he was in his position for life (married, father, middle-aged, con artist). David was both somewhat in awe of Graham, and jealous. I just can't connect the dots as to why Graham would chose that life, if he had better options. Or, perhaps, David brought him into the scam, knowing Graham 'knew that something was good, even though he didn't know why', and Graham was lured in by easy money?
"We got no food, no jobs... our PET'S HEADS ARE FALLING OFF!"