There could be a fanfic where a young witch or wizard stumbles upon a unique wand in Knockturn Alley. Maybe it has a strange origin or hidden powers. The alley is known for its dodgy dealings, so the wand might be cursed or have a dark history. The protagonist could face many challenges while trying to master this wand.
It would probably be a very dark and gritty take on the Harry Potter story. Knockturn Alley is a place full of dark magic and shady characters. Harry might grow up with a different set of values and skills. He could be more cynical and perhaps have a more ruthless streak in his personality.
If Harry Potter lives in Knockturn Alley in fanfiction, it would be a very different story. He could be constantly in danger as Knockturn Alley is full of dark wizards and witches. However, this could also make him more street - smart and better at defending himself. He might learn some spells or potions that are not taught at Hogwarts from the local denizens. And he could have a whole new set of friends or allies who are more on the fringes of the wizarding world.
At first, Snape would probably be his usual sarcastic and aloof self towards Potter. However, as they face the challenges of rebuilding the Alley, like dealing with dark magic traps and uncooperative old - timers, they would be forced to rely on each other. This could lead to a slow thawing of their relationship. Potter might begin to understand Snape's past and the reasons for his bitterness, and Snape could start to see Potter as a capable wizard rather than just James Potter's son. By the end of the rebuilding, they could become something like reluctant allies or even friends.
Well, one possibility in fanfiction is that Harry forms unexpected alliances in Knockturn Alley. Since it's a place full of rather shady characters, he might meet someone who at first seems untrustworthy but actually has valuable information about his past or some dark magic that's about to threaten the wizarding world. It could be a former Death Eater who has a change of heart and decides to help Harry.
Maybe the Ministry of Magic decides that Knockturn Alley needs to be rebuilt and reformed to get rid of its seedy reputation. Potter, with his sense of justice, and Snape, with his in - depth knowledge of the dark arts, are chosen for the task. Potter could use his Gryffindor courage to face the challenges like the resistance from the old - time Knockturn Alley residents who don't want change. Snape, on the other hand, uses his skills to deal with any dark magic remnants. In the end, they not only rebuild the Alley but also create a new, safer place for magical folk.
The Dursleys would likely be out of the picture, or at least not as significant. Instead, Harry might be under the care of some dark wizard or witch in Knockturn Alley. His Hogwarts professors would probably view him with more suspicion. His friends, if he made any at Hogwarts from the more 'good' side, would be initially very wary of him.
The plot could involve a wand that has a special mark on it. The main character finds it in Knockturn Alley and realizes it's different from other wands. It might be a wand that was once owned by a powerful dark wizard. The character then has to decide whether to keep it and try to use it for good or get rid of it to avoid the potential danger it brings.
At Hogwarts, Harry has the safety of the school rules and the guidance of his teachers. In Knockturn Alley in fanfiction, he has to rely on his own instincts more. There are no strict school rules to protect him.