For example [vaguely]: writer creates a character who behaves like X, despite nobody actually behaving like X in real life. Then characters behaving like X become a wide-ranging trope. People in the real world begin to think it’s normal to behave like X, and subsequently start actually behaving like X themselves.
Any actual examples of this phenomenon happening?
A British writer named Nick Cohn wrote a story in 1976 for New York magazine. He’d gone to a couple of local discos and made up most of the story. The article became the movie ‘Saturday Night Fever,’ and the rest is history.
Punk rock started in America, with people who were sick of the overproduced music they heard. A Brit named Malcolm McLaren heard the phrase and ‘invented’ the Sex Pistols band out of his own imagination.
Going back further, the riot that told America they were about to be invaded by motorcycle demons was another example.
https://en.wikipedia.org/wiki/Hollister_riot
Kind of… it was originally used by music critics as a long after-the-fact term for 60s garage-band and surf-rock music, which had a low barrier to entry and a significant DIY element. The 70s musicians who built on those styles were generally much more knowing about their esthetic, and the diversity of styles within the mid-to-late-70s punk-rock genre was wide. Just within the NY scene, you had art-rockers like Television and Patti Smith, retro-garage acts like the Ramones, bands like Suicide incorporating electronic elements, and (soon after) power-pop like Blondie, and the girl-group, dance music and novelty-influenced B52s. And some of those had quite sophisticated production and good musicianship, though sometimes with arftul touches to make it seem raw.
It’s also worth noting that the critics were sometimes wrongly ascribing noble-savage qualities to bands that actually had some serious complexity to their music such as the MC5.
He’d also had some prior involvement with the New York Dolls. It’s easy to overestimate McLaren’s significance in the Sex Pistols, apart from their look and McLaren’s undeniable ability to manipulate tabloid outrage. There was already a fashion scene in London that McLaren was able to tap into, and the musicians who could actually play had mainly come up through pub-rock. McLaren’s primary strengths were as a trend-chaser and hype merchant. But as his subsequent career showed, he was never a visionary. John Lydon was better at coming up with new ideas than McLaren was, and Lydon was by no means a genius.
You focused on the trees and lost the forest.
OP’s question was about people actin a particular way that originally seemed ‘unrealistic.’
Whatever the actual music was, it was McLaren et al that got people wearing purple mohawks and using safety pins for jewelry.