But the 42-year-old actor was only talking about the characters they play in a modern-day adaptation of Shakespeare’s Coriolanus.
The pair play rival Roman soldiers in the new movie about a banished hero of Rome (Fiennes), who teams up with his sworn enemy (Butler) to take his revenge on the Italian city.
Speaking of the physical sequences that included a knife fight, Butler tells USA Today: “Ralph put me to the test. It was two of the most intense days of just grappling with one another.
“I wanted to bite his tongue, rips his tonsils out and eat his spleen. The rolling around was almost sexual as well, with a mix of hatred and respect.”
Butler also heaps praise on his 48-year-old British co-star, who also directed the film.
“Ralph was incredibly supportive,” says Butler. “I was entering a world I’m not used to, diving into a Shakespearean movie with semi-classical language.”
He adds: “His excitement for my performance helped. He was specific and layered in what he wanted.”