Motifs in the James Bond film series the degree to which Bond girls are pivotal to propelling the plot forward varies from one film to the next. Five of the Bond girls are "bad" girls (or at least working for the villain) who turn "good" (or switch sides) usually due to Bond's influence. Bond has fallen in love with only Tracy di Vicenzo in "On Her Majesty's Secret Service" and Vesper Lynd in "Casino Royale", but both of them die at or near the end of the respective films. Roald Dahl, a screenwriter of "You Only Live Twice", said he was given a formula to work to
Casino Royale (novel) God, [James Bond] is the dullest name I ever heard." Fleming decided that Bond should resemble both the American singer Hoagy Carmichael and himself, and in the novel Lynd remarks that "Bond reminds me rather of Hoagy Carmichael, but there is something cold and ruthless." According to Andrew Lycett, Fleming's biographer, "within the first few pages ... [Fleming] had introduced most of Bond's idiosyncrasies and trademarks", which included his looks, his Bentley and his smoking and drinking habits. The full details of Bond's martini were kept until chapter seven of the book and Bond eventually named it "The Vesper", after