Haim (band) spotted by musician Jenny Lewis at a jam session in Laurel Canyon, which led to Danielle joining Lewis' touring band. The Strokes' singer Julian Casablancas came to see one of Lewis's shows on tour, and he in turn asked Danielle to play guitar and percussion on his solo tour. Danielle rehearsed with Casablancas' band every day for two months, which she later described as "an eye-opening experience." Following working with Casablancas from late 2009 to mid 2010, she auditioned for a place in Scarlet Fever, the all-female backing band for CeeLo Green. Danielle performed only once with the group, on
Julian Casablancas award. In April 2015, it was revealed that Casablancas had worked on a song with Savages' Jehnny Beth. The collaboration was later announced to be a cover of "Boy/Girl", a 1983 duet by Danish punk band Sort Sol and Lydia Lunch. The music video, directed by Warren Fu, was released on December 4, 2015. The 7" was released through both Cult Records and Pop Noire Records on December 18, 2015. Casablancas also wrote the song "Youth Without Love" for Har Mar Superstar's 2016 album "Best Summer Ever", and is featured on "No One There", a song by Indian-born musician, Hammarsing