Riding on the success of Three AM, Leiberum caught the eye of Lakeshore Records (a division of Warner Bros.) and released her second album, Brand New Morning on that label. Singles from this album sailed to the top of the charts on Rhapsody.com right alongside of Coldplay and Eminem demonstrating just how widespread her appeal had become. Many of the songs from Brand New Morning made their way on to television, including the WB show Felicity. It was the song "Angel on My Shoulder" that she co-wrote and performed for the movie Mean Creek. The movie, which won awards at the Sundance Movie Festival, was the creation of Gretchen's husband, Jacob Estes.

Even though Jacob is a filmmaker and not a musician, she brought him in as an Executive Producer on Siren Songs. Gretchen says that he is passionate about music and she greatly values his opinions, often taking his suggestions about the music as well as the lyrics. Finding a balance, however, she says he knows when to give her space and just let her do her thing. Building on the experience of working together on Mean Creak they pushed forward and worked side by side on the entire album.

Siren Songs is her most personal work to date. Written in the aftermath of her dearest and oldest friend's (Serena Karlan) murder, it explores the deepest and darkest moments of grieving.

It ended up being an incredibly cathartic process for me, although at one point early on I thought that the pain was too much to continue and I considered just dropping the project for a while. However, my dad reminded me that Serena had such a deep love of music, and was such an enthusiastic supporter of my music, and asked me if I thought Serena would want me to wallow in my pain or continue to make music - the answer was obvious.

She cites going deep inside herself as the most evident marker for her growth as a songwriter between Brand New Morning and Siren Songs. Following the advice of her producer, John Gold, who told her lyrics should be "so personal that they are almost embarrassing, that you almost feel like you've revealed too much," she dug real deep and exposed it all this time around.

The title itself has its roots in Greek mythology. Sirens, mythological creatures, would enchant sailors; their distractions would cause them to drown. Gretchen felt her own songs, lush and beautiful, but conceived from such a dark place, were an appropriate analogy to the myth. For a time she had considered naming the album Serena Songs and notes the similarity, "I liked that 'siren' sounds similar to 'Serena'."