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
Vesper (cocktail) it the "Vesper". At the time of his first introduction to the beautiful Vesper Lynd, he obtains her name in a perfect "interrogation indirecte", "I was born in the evening..on a very stormy evening..," and asks to borrow it. A "Vesper" differs from Bond's usual cocktail of choice, the martini, in that it uses both gin and vodka, Kina Lillet instead of the usual dry vermouth, and a lemon peel instead of an olive. Although there is a lot of discussion on the Vesper, it is only ordered by Bond once throughout Fleming's novels – although Bond drinks the "Vesper"