Shadow of the Thin Man

From a Dissolve article about comedic detectives:

"And the Charleses remain a magnificent comic creation; a loving couple who enable each other’s best and worst traits. Light TV mystery shows have been trying to copy that chemistry for decades, with limited success."

I suspect the first sentence explains the second one. The Charleses work not only because of the chemistry of the leads (which, boy howdy) and their covetable lifestyle, but because the two characters amplify each other. It seems to me that most film and tv romantic characters either "make me a better person" or "bring out the worst in me." It's got to be both. Or it's not funny.