Katie Couric Gets Kinky With EL James, Talks Fifty Shades of Grey Movie

Katie Couric sexed up her talk show Monday in honor of Erika Leonard, a.k.a. Fifty Shades of Grey author E L James, and not just with sensual crimson lighting.

Couric herself drew cheers when she appeared at the top of the hour in a sleeveless black leather dress and sky-high stilettos - to Rihanna's "S&M," obvi.

"Relax - this won't hurt at all," the host joked, introducing herself as our "mistress" for the day ... we should be so lucky. As for her guest of honor?

50 Shades of Katie Couric

EL James is a shy, normal-looking lady in her 40s who speaks softly and is just about the total opposite of who you would expect wrote the bestseller.

James, as shocked as anyone by all the attention her work is getting, was asked who she'd pick to star in the upcoming Fifty Shades of Grey movie.

She was coy about this query, saying only that she has three unnamed actors and four actresses in mind for who should play Christian and Ana. Hmm.

According to Katie's Facebook polls, fans would love Gilmore Girls' Alexis Bledel and Vampire Diaries star Ian Somerhalder ... Matt Bomer is also a popular pick.

Who would you like to see in the lead roles? Tell us below, and follow the jump for a clip of James answering fan questions on yesterday's Katie ...