Luke and Leia had a brief affair in real life.

Last year, Carrie Fisher revealed her affair with co-star, Harrison Ford, on the set of Star Wars: A New Hope. Apparently, she has one more secret that she brought to the grave.

In time for the worldwide release of Star Wars: The Last Jedi, Fisher's on-screen twin and long-time friend, Mark Hamill, has revealed that he and the late actress hooked up while filming of their first movie together.

Undeniable Chemistry

Hamill recounted the story in an interview with The Guardian. According to the 66-year-old, there was evident chemistry between him and Fisher while filming the first Star Wars movie, but he knew that it was a bad idea to get involved with a co-star.

However, that did not stop the young actors from hooking up anyway.

"I remember one time — I'm sure alcohol was involved — we were talking about kissing techniques. I said: 'Well, I think I'm a fairly good kisser. I like to let the women come to me rather than be aggressive.' And she said: 'What do you mean?'" Hamill added, "Well, next thing you know we're making out like teenagers!"

Their makeout session did not end with either of them falling in love. Hamill said that they were very aware of what they were doing and they bursted out laughing. Instead of being lovers, they forged what has become one of the most enduring friendships in Hollywood.

Fisher And Ford

Fisher, a memoirist, left out this bit of information from her books. In 2016, the late actress published the diary she wrote while filming what would become one of the most successful movie franchises in the world. 

The book titled The Princess Diarist revealed her affair with Ford when he was 33 years old and she was 19 years old. 

Hamill admitted that he did not know that his co-stars were hooking up while filming the sci-fi movies. It was Marcia Lucas, wife of director George Lucas, who told him about the relationship after they were finished filming. 

'Star Wars: The Last Jedi' Opens

This week, Lucasfilm released Star Wars: The Last Jedi. The eighth installment directed by Rian Johnson received rave reviews from movie critics and fans of the popular franchise. On Rotten Tomatoes, the movie has scored 93 percent.

According to estimates, the movie is set to earn up to $215 million in its opening weekend in the United States and $440 million worldwide. In comparison, its predecessor, Star Wars: The Force Awakens, opened with almost $250 million during its first weekend. 

Star Wars: The Last Jedi also stars Daisy Ridley, Adam Driver, John Boyega, Oscar Isaac, Domhnall Gleeson, Gwendoline Christie, Kelly Marie Tran, Benicio del Toro, Andy Serkis, and Laura Dern. The movie opens on Dec. 15.