"I've been wanting to do this story for a long time and there was never a German dentist-bounty hunter in the story. The next thing I know, I sat down and wrote that opening scene, and he just flew right out of the pen, like it was the tenant of God, boom!" Tarantino told reporters in New York while promoting "Django" before its theatrical release late last year.
Waltz earned matching Best Supporting Actor Oscars for his performances in "Django" and "Basterds." Tarantino scored the Best Original Screenplay Oscar for "Django," which was also nominated for Best Picture.
"I had this same problem with Sam for about a decade," Tarantino said at the press conference, referring to Samuel L. Jackson, who appeared in "Django," as well as the writer-director's previous films "Jackie Brown" and "Pulp Fiction."
"It's hard not to write for these guys; they say my dialogue so well," Tarantino said of Waltz and Jackson. "For 10 years, I'd write something cool; Bill, for instance.
"For seven months of the year and a half I spent writing 'Kill Bill,' Bill sounded just like Sam," he said of the role that eventually went to David Carradine.
"The way I write, I always kind of fancy it as poetry, and they're the ones that make it poetry; they come out of my pen," Tarantino said. "Sometimes it's not even appropriate, but I can't shut it off."
Asked to describe what it was like to collaborate with Tarantino again several years after their last effort, Waltz said: "There was no reunification and there was no 'working again.' This was just another mushroom of the fungus that was growing subcutaneously in me, all the time."
Waltz was a little less cryptic, however, when pressed to talk about what external sources he used to develop his character, Dr. King Schultz, in "Django," a blood-soaked 19th century America-set, slave-revenge picture.
"In a way, I think 'outside source' is a contradiction in terms. I can only speak for myself, but the source is the script. The script has a source; I can point it out to you," Waltz said, waving at Tarantino's head.
As for the physical training he did for the role?
"I worked very hard, and succeeded most gloriously in falling off a horse, very quickly," Waltz recalled. "This was very early on in the training. Then on, my work was a little slower for the first few months, then I got back up on the horse."
"Django Unchained" is now available on DVD and Blu-ray.
Notable deaths of 2014 [PHOTOS]