Two quarts, every day. That’s the milk drinking way. It’s the beverage of choice in Leon: The Professional (1994), a film that introduces its titular hitman as a sweet, lactose-loving man within the first few minutes. After Léon (Jean Reno) finds himself the unexpected caretaker of 12 year-old Mathilda (Natalie Portman), she convinces him to teach her the tricks of his assassin trade. Drinking milk comes with the regimen.
So what’s up with the milk?
On the surface, the milk is visually ironic. Léon is a master hitman. He’s a big, strong man who does airborne crunches with his legs wedged under a dinner table. He can disappear in and out of a location to assassinate a dozen men without being seen - and then he goes home to drink some milk. It’s not what one expects, and adds a layer of complexity to his persona.
Metaphorically, it’s a symbol of wholesomeness and his paternal concern for Mathilda. He attempts to enrich her and provide her with a more wholesome environment, and milk represents those qualities. It’s a fluid of life, nurture, and care.
Additionally, it’s a fluid of innocence and, in the case of both Léon and Mathilda, childhood. Léon represents childhood in the ways that Mathilda does not; he does not know how to read, he finds great pleasure in simple entertainment, he has no apparent sexual desires or relationships. He is, on many levels, more immature than Mathilda. And she, though an actual child, is intellectually superior to Léon, dresses beyond her years, and is raised in an environment that exposed her to many things children shouldn’t have to deal with.
Director Luc Besson puts a lot of emphasis on the relationship between Léon and Mathilda, focusing on the contrasts between gender, size, physical strength, intellectual strength, assertiveness, confidence, and knowledge. The milk is a metaphor that helps build those comparisons between its two main characters.