There could be a group of rogue Death Eaters who escaped justice and have banded together again. They believe that Voldemort's ideas were right but that he was too weak. So they target Harry, thinking that if they can defeat him, they can finally achieve their goal of a pure - blood - dominated wizarding world. They might be more cunning and less flashy than Voldemort, making them a more difficult enemy to detect.
It could be a new dark wizard who has emerged in Harry's new life. This wizard might be jealous of Harry's fame and want to take him down.
One possible plot could be that Harry discovers he has a long - lost relative who was a powerful wizard but had been exiled for some reason. This relative has left behind a set of magical tasks for Harry to complete that will lead him to a new kind of magic that he's never known before. It could involve traveling to far - off magical lands and making new allies.
There could be a new professor at Hogwarts. Maybe a young and brilliant wizard who has just returned from a long journey in a far - away magical land. This professor could bring in new ideas and spells, and become an important figure in Harry's new path.
The main character could also be a new character introduced into the fanfic's universe. For instance, in a Lord of the Rings - style fanfic, a young elf who has grown up in a secluded part of the forest. One day, they decide to leave their home and start a new path, which leads them to get involved in the larger events of the war against Sauron, perhaps by forming an alliance with humans and dwarves.
The main antagonist could be a powerful necromancer who combines the dark arts of Skyrim with some elements of Voldemort - like magic. He could be raising an army of the undead and causing chaos across Skyrim, which Harry has to stop.
It could be a new dark wizard who has a vendetta against Harry. This wizard might use a spell to stop Harry from eating, thinking it will weaken him before a final showdown. He could be someone who was once a follower of Voldemort and now wants to take his place and prove himself by getting rid of Harry.
Maybe an ancient evil spirit that was once bound but is now trying to break free by using the summoner as a conduit. This spirit could be manipulating events from the shadows, causing chaos in the wizarding world to draw the summoner out.
A former Death Eater who has had a change of heart could be the main character. They are now trying to make amends and start a new life. Their past experiences would make them a complex and interesting character as they struggle to fit into the new, post - Voldemort wizarding society.
It could still be Voldemort, but in a different form. Maybe he has a new power or a different plan this time. Since it's a new chance, he might have found a way to come back even stronger and more devious than before.
It could be a young adult who has just graduated from college and is starting their first job, so they are beginning a new path. The 'lemon' could be their quirky roommate who makes their new living situation interesting.