[Potential spoilers below, so proceed with caution.]

J.R.R. Tolkein never wrote about a butt-kicking lady elf in his epic 1937 fantasy novel. He sure as heck didn't write about elves — and dwarves for that matter — in love.

But that didn't stop Peter Jackson from making up brand new "Hobbit" character Tauriel, played by Evangeline Lilly, out of whole cloth.

Clearly, Lilly knew this when she signed on. She was cool with it — but she had just one condition, she revealed to Yahoo Movies during a recent interview.

"You have to promise me I will not be in a love triangle," Lilly recalled telling the filmmakers of "The Hobbit: The Desolation of Smaug."

[Related: 'Hobbit' Law: Elf Always Beats Human … and Orc]

You can't blame her. After all, Lilly was embroiled in one of the most epic love triangles ever portrayed on television. On ABC's "Lost," Kate (Lilly) bounced back and forth between Jack (Matthew Fox) and Sawyer (Josh Holloway) more times than we can count. Along the way, she incurred the wrath of fans who felt she was with the wrong guy.

"Hobbit" filmmakers gave their word to Lilly: She wouldn't have to repeat such love-story vertigo on the big screen.

But after shooting was done in 2011 for "The Desolation of Smaug," that promise was broken. "We came back for reshoots in 2012 … and they were like, 'Uh, the studio would really like to see…' And I was like, 'Here we go. Here we go' [shakes her bowed head]. And sure enough I'm in another love triangle."

[Spoiler alert! Last chance to avert your eyes...]

In the "Hobbit" sequel, in theaters now, Tauriel becomes the object of Legolas's (Orlando Bloom) desire. But she also develops a crush on one of the younger dwarves, Kili (Aidan Turner). And, like Kate on "Lost," Tauriel never lets her love life get in the way of showing the baddies what she's made of.



Watch: 'The Hobbit: The Desolation of Smaug' Insider Access - Guess the Feet:

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