Speaking of psychology and human nature, try Agatha Christie’s works, especially the Poirot novels. To quote one of his stories;
Poirot shook his head violently.
“That is the psychology,” said M. Bouc.
“And one must respect the psychology. This crime has a signature and it is certainly not the signature of Colonel Arbuthnot.”
Murder on the Orient Express
Pretty much all of her books are unmatched genius.