Demi Lovato expected Britney Spears to be a diva.

But the 20-year-old 'Give Your Heart A Break' singer has revealed that she and her fellow 'The X Factor' USA judge Britney, 30, have become really close on the set of the reality series and love hanging out together.

She told People.com: "What surprised me the most about Britney is that she's actually really quirky. You kind of expect a legendary pop star [to] sometimes [be], like, a diva or something, but she's really not. She's a sweet, down-to-earth, Southern girl."

Demi also opened up about her relationship with judges Simon Cowell and LA Reid on the show and said that even though they are competing they all have the same goal and she is really happy to be working on the series.

She said: "At the end of the day, it's about the contestants. It's not about us as judges. I think other shows maybe forget that the entire purpose of the competition is to find a superstar, not to get publicity for the wrong [reasons].

"I'm having a lot of fun. It's such a blessing to be on this show. It came at a time in my life where I really needed something to look forward to in my career. It's been an amazing opportunity, and getting to sit next to Britney and Simon and LA has been an honour. [And] Just being able to mentor girls that I believe in is so - I can't explain it. It feels so great."