My first encounter of the red/blue pill dichotomy was the first Matrix film. With social media like reddit, this idea spawned via memesis and certain communities began imitating their interpretations of what it meant for them. For example, the contrasts between r/theredpill and r/thebluepill and all the other subs it may have spawned as well, eg: r/mgtow.

Richard Dawkin's wrote a fantastic book called The Selfish Gene on exploring the difference between memetic and mimetic theory that's worth the read.