Photos: Christina Perri at Billboard Studios
Outtakes from the Christina Perri shoot at Billboard Studios.

The singer/songwriter explains how her love of 'Twilight' led to a hit, her Adult Pop Songs top 10 'A Thousand Years.' Also hear an acoustic version of the ballad.

"I got involved with 'Twilight' in kind of a magical way," says Christina Perri.

"I've been a big fan for years and when I signed a record deal with Atlantic Records, they were doing the writing for 'Breaking Dawn'," the 25 year-old Philadelphia-born singer/songwriter recalls. "They asked me to come in and screen the movie and then write something.

"They were going to give me a shot because they knew what a big fan I was," Perri says.

"So, I saw the movie in this little screening room with, like, all these super-Hollywood-y dudes on their Blackberries not watching ... and I'm in the front row crying the whole time.

"I went straight home and wrote 'A Thousand Years'."

This week, the pretty, swaying ballad bullets at No. 10 on Billboard's Adult Pop Songs chart, marking Perri's second top 10 on the tally. "Jar of Hearts" reached No. 4 last year - and follow-up "Arms" reached No. 13; both songs appear on her major label debut, "Lovestrong.," which bowed at No. 4 on the Billboard 200 last May and has sold 298,000 copies, according to Nielsen SoundScan.

Photos: Christina Perri at Billboard Studios

"Years" bridges the gap between "Lovestrong." and her second set, which she's currently writing.

In the meantime, "Years" is on track to pass more than a million in digital sales this week. Parent soundtrack album "The Twilight Saga: Breaking Dawn: Part 1" has sold 467,000 and spun off another smash, Bruno Mars' "It Will Rain," which soared to No. 3 on the Billboard Hot 100.

"I will never, ever forget this phone call I got. It was like, 'You've been chosen for the soundtrack. You've been chosen for the single. You're going to make a music video with clips from the movie and you're going to go on tour with the cast," Perri remembers.

"I couldn't be more stoked. ('Twilight') is my favorite book, my favorite movie.

"I'm, like, super-happy over here."