"There's a feeling of beautiful luxury about approaching this kind of portrait, because you can come with a Martian's-eye view... We were able to create our own lexicon," she said. For instance, in the film the vampires elegantly cover their mouths and have a strange ritual with gloves that goes unexplained.
At heart, the film is the love story between Adam and Eve, who try to rekindle their love despite living in different places, he in Detroit and she in Tangiers. It is as touching as it is odd.
"We knew we needed to show a long love story ... that was so evolved that what they actually say to each other is the tip of the iceberg of a conversation they've been having for 500 years," Swinton said. "That was very interesting. We wanted to show a couple who are trying to stay together. Trying to live obviously, but also trying to live together."
In one comic moment, Eve looks at a grainy photo where they're both dressed in 19th century clothing. "Our third wedding," she sighs.
The love story between immortal beings also raised philosophical questions for leading man Hiddleston, who said playing Adam was a "fascinating prospect" — a chance of breaking away from the more conventional superhero roles, such as the villain Loki in 2011's Marvel Studios film "Thor," for which he is most famous.
"The idea of exploring love in the context of immortality — is (it) a blessing because it recurs, and what does that do to your commitments?" he said.
When news originally got out that Jarmusch, the director of 1999's dark samurai film "Ghostdog," which was also nominated for the Palme d'Or, was going to do a love film on vampires, many were left unconvinced. But Swinton was not one of them and backed the project from the start.
"I was never surprised," she said. "I felt like saying (Jim) you've been making vampire films for years."
Thomas Adamson can be followed at Twitter.com/ThomasAdamsonAP