To begin with, Hernandez is bold, powerful and a strong element in the criminal world. You have to remember that he's survived 20 years in the cartel business which is, in itself, a major accomplishment. If Mexican news and documentaries have taught us anything, it's that the drug world is hardly a safe profession to get involved in. However, all that aside, let's look at when this character joined the gang so you can have a brief introduction.
Fans of this series will recall that Jorge Hernandez came along in the latter part of Always be a Wolf. At that time, he popped into and out of the book but essentially took over the series as the protagonists in The Devil is Smooth Like Honey and he's continued to do so in A Devil Named Hernandez and the most recent book, And the Devil Will Laugh. (Note that 'devil' is in all the book titles he's the protagonist in)
Fans enjoy this antihero, alpha dog character simply because he is strong, confident and unapologetic. His loyalty lies with his close friends and family which is something that I think many people can appreciate. He would do anything for the people he loves; literally, anything. He's very passionate about life and goes after what he wants with complete confidence that he will get it. It is probably because of this arrogant insistence that in fact, he is so successful.
Of course, he also has a surprisingly sensitive side when it comes to his family. His daughter will often tug at his heartstrings as does his wife, which is something we don't often expect from a gangster type character. You know where you stand with Jorge Hernandez whether it be a pleasant place or not. He is the king.