And what a last name..."The dog".... Angelique likes the good things in life and THRUSH is a means to that for her. They're always claiming (at least in FF) that they pay better than UNCLE. Along with her desire for the good things, I think she has to have an evil streak in her, yet a soft spot when it comes to Napoleon.

With Napoleon I think it's just pure lust between the two of them, the thrill that their lover could kill them at anytime. So besides good sex, there's always the underlying danger element.