David Levithan and Andrea Cremer met each other in Washington, DC, even though that's not where they live. Andrea was pretty certain she wasn't invisible, but David confirmed that fact by introducing her to some other writers, who were all able to see her.
Before writing with Andrea, David had never written a novel with a one-word title. His novels include Every Day, Will Grayson, Will Grayson (with John Green) and Nick & Norah's Infinite Playlist (with Rachel Cohn). You can visit David at www.davidlevithan.com and follow his lover's dictionary on Twitter @loversdiction. He lives just outside New York City.
Andrea's novels include Nightshade, Wolfsbane, Bloodrose, Rift, and Rise. You can visit her at www.andreacremer.com and follow her on Twitter @andreacremer. She lives in New York City, quite visibly.