 With Daydream, Carey began incorporating urban R & B and hip hop into her music, something very noticeable in "Fantasy." After Carey began writing songs for her new album Daydream, she decided to include the hook from the Tom Tom Club song "Genius of Love" into an up-tempo song. Afterwards, Carey and Hall began incorporating the sample into the lyrics and melody she had already produced. Carey described how the idea to sample the song became a reality:
