http://newhumanist.i2p/articles/4448/beyond-good-and-evil-breaking-bad
Tuco, the low-level drug lord that Walt and Jesse tangle with in season one, is deranged and violent because he is a meth addict from a criminal family. Gus Fring, the slick meth overlord who makes his first appearance in season two, is a super-pragmatic businessman – so pragmatic, in fact, that he lives his life in seemingly permanent cover, disguised as the humble owner of a small fast-food chain.