In the context of the story, Tony Marlin demands Amanda's help in seducing Eve because he believes that Amanda possesses the charm and skills necessary to attract Eve's attention. Tony likely feels that he lacks the confidence or the right approach to win Eve over on his own, so he turns to Amanda, who may have a better understanding of Eve's preferences or a more persuasive demeanor.

This dynamic often highlights themes of friendship, manipulation, and the complexities of romantic relationships, where one character seeks assistance from another to navigate their feelings or desires. If you have a specific work or context in mind regarding Tony, Amanda, and Eve, please provide more details for a more tailored response!