One possible way in a fanfic could be that there was a misunderstanding. Hagrid might have been accidentally given a poisoned item by Harry that was meant for someone else. But still, it's a disturbing concept as Hagrid is a beloved character. It could also be that the fanfic was exploring a parallel universe where the characters' personalities and relationships are distorted, leading to this tragic event.
The consequences would be far - reaching. Firstly, Harry would be completely ostracized from the wizarding community. His friends would be horrified and would likely turn against him. He would probably be sent to Azkaban for such a crime.
Maybe in that fanfic's plot, there was a misunderstanding that got out of hand. Suppose Harry was framed for something terrible, and Hermione, believing the false evidence, felt that she had to take drastic action to protect the wizarding world from what she thought was a great threat, so she kills him. But later she realizes her mistake.
Maybe Hagrid will teach Harry all kinds of magical creatures in that summer. He could introduce Harry to the hippogriffs, how to approach them safely and gain their trust.
Well, in a fanfiction world, anything can be possible. Maybe Harry Potter uses his magic skills like the Killing Curse. But it's really a strange crossover. The Joker is from a completely different universe with no magic, and Harry Potter is from a world full of magic. It would be a very unique and perhaps disturbing story to see how Harry Potter overcomes the Joker's chaos and madness with his magic and finally kills him.
Well, one possibility is that Naruto would face some serious consequences. Killing is not in his usual nature, so he might struggle with guilt. Also, the Sound Village would likely seek revenge, which could lead to a full - scale war between Konoha and the Sound. Another thing could be that his friends in Konoha might view him differently, some might be afraid of his new - found brutality while others might try to understand his motives.
Another possibility is a complete character distortion in the fanfiction. The writer might decide to create a 'bad Naruto' version where he has lost all his positive traits. However, this is quite far - fetched considering the strong foundation of Naruto's character in the original series. It would be a very different and probably controversial take on the Naruto - Hinata relationship.
In a Naruto kills Thanos fanfiction, Naruto's sealing techniques could play a major role. He could use sealing jutsu to seal away Thanos' powers or even Thanos himself. Naruto has experience in dealing with powerful foes and sealing them away. Also, Naruto has the ability to sense danger and react quickly. Thanos, on the other hand, may underestimate Naruto at first. By the time he realizes Naruto's true strength, it could be too late for him.
In fanfiction, Naruto might kill a god through the power of his strong will and the unique abilities he has. For example, his Sage Mode could be enhanced to a level that allows him to overpower a god - like entity. Also, his Nine - Tails chakra could be combined with some new, made - up powers in the fanfiction world to give him the strength needed.
Well, in a fanfiction scenario, Naruto might kill Aizen if he manages to use his shadow clones to outwit Aizen's illusions. Naruto could also use his Sage Mode to sense Aizen's reiatsu and counter his attacks. Maybe he combines his Rasengan with some new jutsu he's developed specifically to deal with Aizen's powers.
Well, it could happen if Naruto has some sort of special weapon. For example, he might get a sword that can disrupt Hidan's connection with his voodoo - like powers. Once that connection is broken, Naruto could easily defeat and kill Hidan. Also, Naruto's growth in chakra control and strength could play a role. With his enhanced abilities, he could overpower Hidan and deliver a fatal blow.