There’s a throw away line in John Wick where Viggo calls John, ‘Death’s pupil’. Later on, John refers to himself in the same way, saying how even though he was a pupil of Death, he escaped the life it put him in: a secret world of assassins. An underworld. The line isn’t noticeable but it is the key to unlocking the story’s theme.
John Wick is a retired assassin who found love and escaped the underworld. But when the pristine memory of his wife is tarnished after some cliche Russians kill the only living memento of John’s time together with his wife, he’s forced to return to the underworld so he can exact revenge on those who took his new life away, a selfish kind of justice.
In a way, it reminds me of a Ancient Greek heroes Orpheus and Odysseus who both ventured into the underworld to save their loves.
Thus the premise of John Wick could be ‘No one escapes the underworld, not even Death himself,’ which in a way John is on his path to becoming. We see the way he kills with simple efficiency and somewhat sadism. This is his journey to become Death, which by the third movie, he very much is. He reminds me of a character from a Terry Pratchett novel that takes over Death’s mantle, serving to give the role of the grim reaper a human expression.
So, John Wick’s theme is powerful, Greek-like in its depiction of a hero, but played out in an inversion of expectations of the genre while largely being overshadowed by the necessities of the genre it’s in: Action, baby.