I really wonder why the "brainwashed assassin" trope.
It's a very provocative idea - the person you least expect to be an assassin [usually women, but sometimes also loyal soldiers or w/e] has been insidiously subverted by [insert foreign power or shadowy cabal]. The hidden programming aspect of it has a vibe of "this could have happened to someone close to you, or even you!". I have to imagine that it dovetailed perfectly with cold war paranoia, given that The Manchurian Candidate came out in 1959.
It being the hottest new idea in the 60's is why it was in a stack of spy movies, since spy fiction was in vogue after James Bond broke out in '62. And brainwashing/mind control in general was also rife in the genre.
I suspect that for a lot of the (not so young) people on this site, some kind of brainwashed assassin plotline was part of why they have the fetish, haha.
