Characters like Near might analyze the fanfiction. He'd probably look at the logic behind the plotlines in the fan - made stories and compare them to the real events in the Death Note world. If the fanfiction has a really convoluted and illogical plot, he might dismiss it as being not worthy of his attention. But if it has an interesting take on the characters' motives, he might give it more thought.
Ryuk would probably just be amused. He is a Shinigami who has seen a lot in his existence. Fanfiction is just another strange human creation to him. He might chuckle at some of the more outlandish ideas in the fanfictions, like a character having superpowers beyond the Death Note.
It's possible that the characters would be confused at first. They are used to their own storylines in Smallville, and when they see fanfiction that twists and turns those storylines in unexpected ways, it would take them some time to process. For example, if Oliver Queen saw a fanfic where he was a villain instead of a hero, he would need to wrap his head around this new take on his character.
There are also characters who would be very critical. Characters who value the 'truth' of their own experiences in the zombie - apocalypse world. They would pick apart any inaccuracies in the fanfiction. Maggie, for instance, would not tolerate if the fanfic misrepresented her family relationships or her motives. She'd be quick to point out that the fanfic doesn't match up with what really happened in her life during the events of The Walking Dead.
Harley Quinn might get really into it. She has a wild and unpredictable personality. She could start to role - play some of the scenarios from the fanfiction in real life, much to the confusion or amusement of the other Squad members. It would be in - character for her to embrace this strange new view of their world.
The characters' reactions can vary greatly. A character who is always looking for new challenges might be eager to see how the fanfiction presents them in different situations. They might think it's a cool way to expand their story. On the other hand, a more conservative character may feel that the fanfiction is disrespecting the original story and their role in it. Also, characters might have different feelings based on how well - written the fanfiction is. If it's poorly written, they may just dismiss it, but if it's really engaging, they could be drawn into this new version of their story.
Harry would likely be very conflicted. He has seen a lot of death and has always fought against dark magic. The Death Note's power to kill just by writing a name is something that goes against his values. He would probably try to keep it away from others and might even consider destroying it.
There could also be characters who are a bit skeptical. Dolores, with her ability to hear everything, might be able to tell if the fanfiction is based on real events or just pure imagination. If it's too far - fetched, she might be less impressed. However, overall, most characters would probably see it as a form of celebration of their story and be at least somewhat entertained by it.
They could be either impressed or disappointed. The well - written fanfiction that respects the lore and adds new depth to the 40k universe would impress them. But those that are full of inaccuracies or go against the core values of the 40k world might disappoint them. For example, if a fanfiction portrays a noble character as a villain without proper reasoning, the character might be offended. On the other hand, if a fanfiction explores a new aspect of their backstory in an intelligent way, they would be quite impressed.
Naruto would first be extremely confused by the rules of the Death Note. His understanding of power and its consequences is rooted in his ninja training and his own moral compass. The Death Note's rules, which seem so simple yet so deadly, would be completely foreign to him. He would question why anyone would create such a thing and would be very hesitant to even consider using it, as it goes against everything he stands for in his world of ninjas, friendship, and protecting the innocent.
Some characters would be shocked. Allison, for instance, might be taken aback by how some fanfictions explore her power in different ways. She could be both fascinated and a little bit worried about how fans perceive her use of the 'I heard a rumor' ability.