In some fanfiction, the magic that powers St Mungo's starts to fail. Harry Potter then has to find a way to restore it. Along the way, he discovers that the origin of the hospital's magic is linked to his own family history, which is a big and unexpected twist.
A common plot twist is that St Mungo's is not as safe as it seems. In some fanfics, there are hidden chambers in the hospital where dark magic experiments are being carried out.
One great fanfiction could be 'A Day at St Mungo's with Harry Potter'. In it, Harry might be visiting the hospital for some post - battle check - ups or to see a friend who's been injured. It could show the different wards and the unique magical maladies being treated there.
One interesting plot twist could be that Harry discovers he has the ability to communicate with the Basilisk on a deeper level than just Parseltongue. Maybe he can see through the Basilisk's eyes and use this to his advantage in uncovering secrets within Hogwarts that even Dumbledore doesn't know. Another could be that the Basilisk is not truly a villain but was being controlled by a dark force all along, and Harry has to find a way to break that control and free the Basilisk.
One interesting plot twist could be that the basilisk has an unexpected alliance. Maybe it teams up with a group of outcast magical creatures to take revenge on those who have wronged them. This would completely change the dynamic as in the original, the basilisk is mainly a tool of Voldemort.
In this fanfiction, a great plot twist might be that the gamer's knowledge of game strategies is used to outwit Voldemort in a completely unexpected way. Instead of a traditional magical duel, the gamer uses their understanding of leveling up and collecting power - ups to somehow weaken Voldemort's magic. Maybe they find a way to 'hack' into his dark magic, using skills from the game world that no one in the wizarding world had thought of before.
Well, in some 'Harry Potter and the Prophecy' fanfiction, a plot twist could be that the prophecy was not a prophecy at all but a spell cast by an ancient wizard to set in motion a series of events for a greater purpose. For example, it was to bring about a new era of magic where Muggle - borns and pure - bloods could co - exist peacefully. This would completely change the way the characters view the prophecy and their roles in it. Also, the prophecy might be tied to a different character than Harry or Voldemort, like a minor character who suddenly becomes central to the whole story.
One interesting plot twist could be that instead of Ron leaving and coming back, Hermione actually leaves the group for a while because she discovers a dark secret about her family's past that she needs to figure out on her own. This would add a whole new layer of drama to the story.
One interesting plot twist could be that Neville is actually a secret heir to an ancient magic family. In some fanfictions, he has hidden powers that are awakened in the search for the Sorcerer's Stone.
Well, one possible plot twist could be a revelation about a character's true heritage that was hidden all along. For example, a minor character might turn out to be related to one of the major wizarding families in ways no one expected.
Maybe Harry's parents are alive but they've been working undercover for a long time against a different dark force that is allied with Voldemort. When they come back into Harry's life, they bring with them a whole new set of problems and mysteries. For example, they might have made some dangerous pacts with other magical beings in order to gain information. Harry has to deal with the consequences of these pacts while also trying to keep his family together. Another plot twist could be that they are alive but time - traveling is involved. They've been stuck in a different time period and Harry has to figure out how to bring them back to the present, all while Voldemort is still a threat.
One interesting plot twist could be that a minor character in the original series turns out to be a key figure in the fanfiction's plot. For example, a seemingly unimportant Hogwarts student might be revealed as a powerful wizard with a hidden agenda that affects Harry and his friends.