Paul Schrader encapsulates everything a reader needs to know about his central character.
"TRAVIS BICKLE, age 26, lean, hard, the consummate loner. On the surface he appears good-looking, even handsome; he has a quiet steady look and a disarming smile which flashes from nowhere, lighting up his whole face. But behind that smile, around his dark eyes, in his gaunt cheeks, one can see the ominous stains caused by a life of private fear, emptiness and lonliness [sic]. He seems to have wandered in from a land where it is always cold, a country where the inhabitants seldom speak. The head moves, the expression changes, but the eyes remain ever-fixed, unblinking, piercing empty space.
Travis is now drifting in and out of the New York City night life, a dark shadow among darker shadows. Not noticed, no reason to be noticed, Travis is one with his surroundings. He wears rider jeans, cowboy boots, a plaid western shirt and a worn beige Army jacket with a patch reading, 'King Kong Company, 1968-70.'
He has the smell of sex about him: sick sex, repressed sex, lonely sex, but sex nonetheless. He is a raw male force, driving forward; toward what, one cannot tell. Then one looks closer and sees the inevitable. The clock spring cannot be wound continually tighter. As the earth moves toward the sun, Travis Bickle moves toward violence."
Paul Schrader's Taxi Driver, written in 1972, published by Faber and Faber, 1990, page 1.
Reading the script, it's striking how literary and ambitious it is. This shouldn't be surprising I suppose, since Schrader had been an incisive film critic steeped in the most serious European modernist and Japanese cinema for many years, and the survivor of a particularly muscular Christian upbringing. Surely, the anti-Tarantino.
It is also unconventional in format, lacking the usual scene and location cues and divided into titled chapters, which only increase the intensity of Travis' deterministic downward spiral. The sense of surprise comes from the disjunction between the pulpy subject matter and the tone of thematic seriousness; Travis as a 1970s Raskolnikov.
Reportedly, De Niro flew back to New York from Rome during breaks on 'Novecento' and drove a cab for several weeks in preparation.