On December 30, 2004, Spears made a surprise appearance at Los Angeles radio station KIIS-FM to premiere a rough mix of a new midtempo track, "Mona Lisa". Spears had recorded the song live with her band while on tour, and dedicated it to all the "legends and icons out there." The lyrics lament the fall of Mona Lisa, calling her "unforgettable" and "unpredictable," and cautions listeners not to have a "breakdown". She also revealed she wanted the song to be the first single of her upcoming album, tentatively titled The Original Doll, and hoped to release it "probably before summertime , or maybe a little sooner than that." In January 2005, Spears posted another letter on her website, saying,
I think I should rephrase myself from my previous letters when I was talking about taking a 'break'. What I meant was I am taking a break from being told what to do. ... It's cool when you look at someone and don't know whether they are at work or play since it's all the same to them. The things I've been doing for work lately have been so much fun, because it's not like work to me anymore. I've been even more 'hands on' in my management and the business side of things, and I feel more in control than ever.
A representative for Jive Records stated that although Spears was working in the studio, "no album is scheduled at the moment" and "there are no plans to service 'Mona Lisa' to radio." "Mona Lisa", written by Spears, Teddy Campbell and David Kochanski, was later re-worked and released in a bonus CD included in the DVD of Britney & Kevin: Chaotic. "Someday (I Will Understand)", also included on the bonus CD, was composed by Spears on the piano at her house, two weeks before she learned of her pregnancy with her first child, Sean Preston. She explained the song came "like a prophecy... when you're pregnant, you're empowered". She gave birth to her first son, Sean Preston, on September 15, 2005.Guy Sigsworth was the producer of "Someday (I Will Understand)", and he also co-wrote a song with Imogen Heap, Robyn and Alexander Kronlund, titled "Over to You Now", that was included as a bonus track to the bonus CD. "And Then We Kiss" was set to be included on a bonus disc too, but was left out for unknown reasons. The bonus CD was released as Spears' first EP on September 27, 2005.
"Someday (I Will Understand)" was released as the first and only single from the bonus CD of Britney & Kevin: Chaotic in Europe on August 21, 2005. The song reached the top ten in Denmark, Sweden and Switzerland and also charted in a number of European countries. The black-and-white music video premiered on the finale of Britney & Kevin: Chaotic. Directed by Michael Haussman, it features Spears as a pregnant woman and portrays a transformation of her character. A remixed version of the song was included on the 2005 remix compilation, B in the Mix: The Remixes. The theme song, "Chaotic", received a promotional release in Japan, despite not being released as a single.