Making a murderer, David Fincher

Movie assassins tend to move through the world like chic land sharks: sleek, ruthless, undetectable until it's too late. But the numerous quirks of the nameless lead portrayed by Michael Fassbender in David Fincher's latest film, "The Killer" (streaming on Netflix), defy the genre stereotypes of a suave, soulless hit man.

Instead, screenwriter Andrew Kevin Walker, adapting from a French graphic novel series by Alexis Nolent, said via Zoom that he deliberately designed his bucket-hat-wearing, McMuffin-eating muse as "the anti-James Bond, almost alien."

He added, "The fact that he doesn't care whether his drink is shaken or stirred makes sense for his character. We wanted him to hide in plain sight."

Below, how to build an oddball executioner in seven easy steps.

Embrace your inner monologue

While the Killer is loquacious in voice-over -- cheerfully unspooling a life philosophy that pulls from both Popeye ("I am what I am") and 20th-century occultist Aleister Crowley ("Do what thou wilt shall be the whole of the law") -- he hardly speaks in the presence of other characters onscreen.

"When Fincher told me the story initially," Walker recalled, "he said, "The whole thing's going to look like an amazing perfume commercial from beginning to end, and I want him to say literally 10 lines of spoken dialogue."

So it's essentially a silent movie when it comes to his performance, except for all this voice-over."

Dress for anonymity

How do you make a 6-foot-tall movie star with a cut-glass jawline blend into the background? Outfit him like a guileless tourist. The Killer's goal is to become human wallpaper, essentially, 'so 'tourist' is what made sense," Walker said. "And it was always definitely going to be a bucket hat, because it's such a dopey little hat."

Eat like nobody's watching

To see Fassbender's character casually strip a McMuffin down to its proteins or squeeze prepackaged hard-boiled eggs into his mouth like a snake swallowing a dormouse is to witness a man who eats strictly for fuel, not pleasure.

"What do you get for your dinner when you're walking to Starbucks?" Walker asked. "There are choices there, but for him, he's deconstructing almost every one of those choices. Obviously, a lot of what he does is just functional. I love when he's eating a banana and drinking Ensure -- that is his fine dining."

Exercise efficiently

His routines may be rigid, but his spinal cord is a Slinky: Fassbender's backbends, yogic sun salutations and fingertip pushups reveal a Killer used to a DIY fitness routine. On a stakeout, "this guy ain't going to be traveling with barbells," Walker said.

"He's probably not even going to have one of those stretchy resistance bands that you see him with in one scene, and then five scenes later he's using it to strangle someone. If he's in a room full of art, he's walking past the art, he doesn't even look at it. But if he's going to spend four days in this same room, how is he keeping in shape?"

Borrow all the famous names you need

Felix Unger, Lou Grant, Sam Malone, Robert Hartley: If you're checking the Killer's multiple IDs, you'll find a pile of pop-culture aliases that include characters from TV touchstones like "The Odd Couple," "Cheers" and "The Bob Newhart Show."

"Whatever he's leaving behind, there's meant to be a trail that couldn't be followed," Walker explained. "So once I knew he had to be giving his name to get a plane ticket or using a credit card to get a gym membership, that's when I hit upon these [fictional figures] that mean a lot to me. I just love that two of the names come early enough that you know there's going to be this reoccurring tip of the hat."

Keep the soundtrack consistent

"There was a certain point where Fincher decided the music should be all '80s, so they tried different things, and the Smiths is just so in keeping with his character," Walker said of the Brit-rock demigods whose warbling ballads consistently fill the Killer's headphones.

"He doesn't, in my opinion, listen to music too much for pleasure. It's something to occupy a certain level of his subconscious, and since he spends so much time alone, maybe his thoughts don't rattle around in his head so much when there's music in his ears. It's like the cliché of the person who wears the same suit every day so they don't have to waste time thinking about it. This is his closet of music."

Eyes on the prize

Though theater audiences might miss it in real time, Netflix viewers can replay and pause on one particularity: Fassbender rarely bats an eyelash -- literally. "You don't really notice, but if you were to play 'The Killer' blinking-drinking game, you would be pretty sober by the end of the movie," Walker revealed, adding a colorful word before "sober" for emphasis. "And that's amazing. It was just this little tiny thing in the script, and they ran with it."