In that fanfiction, it could be that a character who was secretly working for Voldemort, perhaps someone we didn't suspect at first, like a seemingly innocent teacher or a student who was under the Imperius Curse. Another option is that a group of dark wizards invaded Hogwarts and Harry was unfortunately caught in the crossfire and killed. Or perhaps a magical artifact malfunctioned and ended up being the cause of his death.
Quirrell could be the main villain. He was already under Voldemort's influence in the original story. It's possible that in this fanfiction, he doesn't hold back and attacks Harry more directly and lethally during his first year. Maybe he uses his position as a teacher to get close to Harry and then strikes when he has the chance.
If Harry died in his first year in that fanfiction, it would likely mean that the prophecy would be unfulfilled. This could lead to a different kind of power struggle in the wizarding world. Dumbledore's plans that were centered around Harry would be in ruins. Also, characters like Snape might have different fates as their relationship with Harry was a big part of their development. It could also mean that the Deathly Hallows would remain untouched or be used in different ways by other characters.
Perhaps it's a shy and introverted first - year who has some sort of hidden power. Harry spots this potential in the student and adopts them. The first - year could be from a pure - blood family that has fallen on hard times. His or her name could be Oliver, and Harry sees in Oliver a chance to change the negative image some pure - bloods have.
Well, it could be for the sake of exploring a different kind of magic or a different set of rules in the wizarding world. Perhaps in this fanfiction's version, the parents were under some sort of dark magic influence that made them turn on Harry. Or it could be a psychological exploration. The writer might be interested in delving into the minds of Harry's parents and seeing what could make them do such a heinous act. It could also be just a very different take on the concept of family and love in the 'Harry Potter' universe.
One possible plotline could be that the troll in the bathroom attacks Harry more brutally and he succumbs to his injuries. Another could be that Quirrell, being a servant of Voldemort even earlier, manages to directly attack Harry and kill him before he has a chance to figure out what's going on. Maybe there's a dark wizard who infiltrates Hogwarts on the very first day and targets Harry specifically, seeing him as a threat even at that young age.
Maybe it's a jealous student from Hogwarts. Someone who is envious of Harry's fame and power. This student has been studying dark magic in secret and decides to kidnap Harry to prove that they are better. They take his glasses to humiliate him as well. They might think that without his glasses, Harry is just an ordinary wizard and they can easily overpower him.
One great fanfiction could be 'Back to the Beginning' where Harry travels back to his first year and tries to change some small events that he later realizes have big consequences. It has really interesting character interactions and a unique take on how time travel works in the Harry Potter universe.
Maybe in this fanfiction, some dark magic forces manipulated the situation. They could have lured Harry Potter into a dragon - infested area and set up some powerful spells that prevented him from escaping, thus forcing him to face the dragon which ultimately killed him.
In the finale of the first chapter of the celebration of the past few years, Fan Xian had been pierced through by Yan Bingyun's sword. In reality, this was only a trick that Fan Xian and Yan Bingyun had conspired to make themselves suffer. Fan Xian had not really died. Through his own cultivation and Yan Bingyun's sword technique, he created a fake death scene and successfully confused everyone. After Fan Xian fell to the ground, the Second Prince appeared and praised Yan Bingyun before leaving. After that, Wang Qinian appeared and rescued the heavily injured Fan Xian. He took him to the thatched cottage where Haitang Duoduo lived. Therefore, according to the information provided, Fan Xian had not really died.
In the finale of the first chapter of Qing Yu Nian, Fan Xian was stabbed to the ground by Yan Bingyun. His life and death were unknown. However, according to the plot and the setting of the original work, Fan Xian did not really die. This was a trick that Fan Xian and Yan Bingyun had set up together. Their goal was to save Fan Xian in a difficult situation. Thus, Fan Xian did not truly die.