Isolation is another theme. Shigaraki is often depicted as a lonely figure. Fanfics may explore how his isolation affects his actions and decisions, and how relationships (or lack thereof) shape his character in the BNHA context.
One great 'bnha shigaraki fanfic' is 'A New Path for Shigaraki' on FanFiction.net. It delves deep into his character, exploring his backstory in a unique way and showing his potential for redemption. The writing is engaging and the plot is full of twists.
The Bnha universe's reaction would be mixed. Those who are into complex stories, like Todoroki, might study the relationships in Hamilton fanfiction. But others, like Mineta, might not be interested at all because it doesn't have much to do with his usual interests. Overall, it would depend on the individual characters' personalities and interests.
Some would be inspired. Characters like All Might might see Peter Parker's journey as similar to his own in some ways. Both are trying to do good in a world full of challenges. All Might could appreciate Peter's determination to protect his city despite having a normal life outside of being a hero.
For heroic - centric fanfictions, they would likely be disdainful. Since they oppose heroes, seeing stories that glorify heroes would annoy them. They might scoff at the idealized versions of heroes in those fanfictions.
Shigaraki is not dead in the manga. The storyline has many twists and turns, and his character plays a significant role, so his survival adds to the ongoing drama and suspense.