In some scenarios, they might die heroically in a big battle against dark forces. For example, while protecting Hogwarts, they could be outnumbered by powerful dark wizards.
It could be that the Weasley family sacrifices themselves to save others. They are a very selfless family in the original series. So in this fanfiction, they might choose to give their lives to protect their friends, neighbors, or the whole wizarding community from a great danger like a powerful dark magic weapon.
In some fanfictions, Spiderman might die due to a miscalculation in his powers during the battle in Civil War. Maybe he tries to overextend himself to protect civilians or other heroes and gets caught in a cross - fire that his body can't withstand.
Another scenario could be that Gohan contracts a deadly and incurable disease in the fanfiction world. Despite the efforts of his family and friends, including the use of any available advanced technology or magic, he succumbs to the illness, leaving everyone in mourning.
One possible scenario could be that Naruto was severely injured in a battle, perhaps against a powerful new enemy. He was brought to the hospital, but his injuries were too grave to be healed, and he passed away surrounded by his friends and family, leaving everyone in deep sorrow.
One possible scenario could be that Luffy sacrifices himself to save his crew during a major battle against an extremely powerful enemy. He might use all his strength and energy to protect them, and in the end, it's too much for his body to handle.
It would be a huge loss. The Weasley family is well - known and loved. Their deaths would cause great grief among their friends and allies. It might also lead to a decrease in morale among the good wizards.
One possible scenario could be that Edward sacrifices himself to defeat a powerful and final enemy. He might use up all his alchemy knowledge and power in one last, desperate attempt to save the world, and his body just can't take the strain.
One possible scenario could be that they sacrifice themselves to save the village from an ultimate evil. They might combine their powers in a final, desperate move that exhausts them completely, leading to their deaths.
One possible scenario could be that Peter sacrifices himself to save others during a crucial battle in the Endgame - like situation in the fanfiction. Maybe he uses his powers to hold off a powerful enemy while the rest of the heroes complete a vital task.
One possible scenario could be that Tony is in Siberia on a mission gone wrong. Maybe he's facing a powerful enemy there, and despite his best efforts, he gets fatally injured in a fight. Another could be that the harsh Siberian environment plays a role, like he gets caught in a blizzard and succumbs to the extreme cold.
One possible scenario could be that Percy sacrifices himself to save Annabeth from a powerful and deadly monster. Maybe a huge and ancient sea creature that only Percy can hold off long enough for Annabeth to escape, but at the cost of his own life.