But all that work could scarcely ready him for the intense reality of performing a slave's labor in a Louisiana summer.
"Then you're there on the first day and it's 108 degrees and you're picking cotton," says Ejiofor. "How is that accomplishable? I don't know how to do this without delirium setting in. Then you realize: Now we're in it. This is what this is. It is a delirium. It is down the rabbit hole."
Ejiofor's titanic and steadfast performance in Steve McQueen's unblinking portrait of mid-19th century slavery has already been hailed as the performance of Ejiofor's career. After Fox Searchlight releases the film Friday, Ejiofor is likely to become a fixture on the fall awards circuit, a best-actor Oscar nominee and a name pronounced with considerably more familiarity.
Many have already known the 36-year-old British actor's strong, sensitive presence from Stephen Frears' "Dirty Pretty Things," Alfonso Cuaron's "Children of Men" or, on the London stage, as an acclaimed Othello. But "12 Years a Slave," which Ejiofor initially hesitated at taking on, is unique in its challenges.
The film brings audiences along on Northup's nightmarish journey, taken from his family in Saratoga Springs, shipped south and traded among plantations of varied ugliness. (Michael Fassbender plays Edwin Epps, an especially monstrous cotton plantation owner.) The film, perhaps more than any before, depicts the plain, inhumane realities of slavery, including long takes of a beating and when Northup was left hanging by a noose all day long, tiptoeing frantically to stay alive.
One expects such a psychological descent to scar an actor, but playing Northup had the opposite effect on Ejiofor.
"I felt enriched by being in Solomon's shoes for so long," he says. "Going to that place was so fascinating and there was such a strength and dignity and duty to Solomon and his soul and his survival instinct that I felt there was as much to take away from it that was redemptive as there was that was harsh or difficult."
With deep, soulful eyes, Ejiofor captures Northup's indomitability, his undiminished integrity. McQueen, the British director of "Hunger" and "Shame," compares Ejiofor's dignified genteelness to Sidney Poitier.
"There's a humanity to him, which would obviously be tested to a breaking point in this film," says McQueen. "I was thinking that he could hold it together, that he could get to the finishing line."
Ejifor's parents, a doctor and pharmacist, immigrated to the United Kingdom from Nigeria. His family fled during the Biafran war of the 1960s, the very backdrop of a film Ejiofor recently shot in Nigeria: "Half of a Yellow Sun." ''It's the reason I'm sitting here," he says of the war that brought his family to Britain.
Ejiofor's father, who was also a popular musician ("a deeply good natured man," he says) died in a car accident on a return trip to Nigeria, with Ejiofor in the car. Eleven at the time, Ejiofor has a scar above his left eye from the crash.
The actor's first film, ironically, was Steven Spielberg's slave uprising tale "Amistad" (Ejiofor played a translator). But instead of staying in Hollywood afterward, the 19-year-old returned to London to work in theater, he says, "to get my feet firmly planted on the ground."
With a warm chuckle and an inviting openness, he still exudes that humility. Fassbender calls him "the perfect partner to dance with."
"It takes an extraordinary person as well as actor to be Solomon Northup, and take the audience in the mirror-image sort of way, through this story," says Fassbender.
Ejiofor recalls at one point being so emptied during the shooting of "12 Years a Slave" that he would, rather than walk 10 feet to a bench, lie on the floor as the camera and lighting were adjusted. But the actor says it was essential to show, in full, the brutality Northup endured to be faithful to his story.
"If you don't get inside that experience of being there all day, out in the sun, hung by your neck, just barely able to stay alive, then you don't know the depth this man is prepared to go to in order to keep himself alive," says Ejiofor. "Then again, you don't understand Solomon."