The classic hero tale always features heroes who have to make tough decisions, and The House of the Scorpion is no different. Just as Frodo decides to take the one ring to Mount Doom rather than try to, say, sell it on eBay, so our Matt must face his own struggles and return home to take control of Opium. Matt doesn't go to battle in any kind of traditional way. There's no sword in a stone or magic wand he pulls out to duke it out with El Patrón. Matt might be a hero on a grand scale (he does take over an entire country by the novel's end), but he's also a young boy with no special gifts. Instead, Matt makes choices of a more realistic variety. He fights El Patrón by growing up to be a good, strong person. He's come into his own and out from under El Patrón's shadow, all by calling his own shots in life.
One of the major lessons that Matt learns is this: just because you can do something, doesn't mean you should choose to do it.
Based on whether or not they choose help Matt, you can tell whether characters are good or bad.