I've been close friends with Katy since teenagers, before she was Katy Perry. She's always been a great resource for me to pull from and watch - from her choice of how public she wants to be about her personal life on down. I also watched her develop from the coffee-house singer-songwriter I knew to her be to playing arenas and killing it.

Obviously I love writing with Katy [Pery], I feel like we're the same person when we write together. Even though we fight a lot, we fight over every line and we pull each other's hair and we cat-fight all the time, it's always worth it in the end.

I was writing songs as a kid about leprechauns and Catwoman and teapots - whatever it is that little girls wanna sing about. The first song I wrote was called "Kitten." It was about a boy named Liam, who I was just crazy about.

In my head, I wanted to be Madonna, but the music I was writing on paper was not what you'd choreograph dancers in costumes to. It was more coffee-house stuff.

I tend to get a little quirkier and crazier with my lyrics and come from a different angle when I'm writing for myself.

I like to go to the movies at The Hollywood Forever Cemetery. They do this thing in The Hollywood Forever Cemetery in Hollywood where everybody sits out on the grass and they project movies and it's very romantic and very old-school Hollywood, so I love that.

When I go and write with other artists - a lot of the time it's with them - it's like a therapy session almost. I ask them what they're listening to and what they're going through and what their influences are and I try to get inside of their head and step into their shoes for a second.