One thing that hasn't exactly evolved for Perry, but which she tries to put to good use: "I'm very OCD and I don't say that lightly," she informed Paper magazine this year, connecting the dots between her clinically diagnosed condition and instability and trauma in her childhood.

"It was just a product of me trying to control my environment," she added. Perry said that she went to therapy regularly, usually alone but she had gone with her parents before, and she took great comfort in being able to help them out thanks to the fruits of her success.

"I feel so grateful to be able to do it," she said, "because that's all you ever want. You want the kids to be able to sing the words that you wrote back to you, and then also to just buy your mom a house. Or have them not fight over money anymore. If you can remove that feeling, it feels like you... maybe somehow you've healed some part of your childhood."