There's a fanfiction where the Weasley twins create a 'Scared Straight' program for first - year students. They use their magical pranks in a new way to teach the young students about the consequences of misusing magic. Harry gets involved in helping them out. It's full of the twins' humor but also has a serious undertone about the importance of responsibility in the wizarding world. It's unique because it focuses on the students themselves taking the initiative instead of the teachers or adults.
I've read one where Voldemort is resurrected early but instead of going on a rampage right away, he decides to use a 'scared straight' approach on the wizarding world. He targets the Hogwarts students, especially Harry and his friends. He shows them visions of a future where dark magic has completely taken over if they don't start behaving better. It's a really unique take on the relationship between the good and the bad in the wizarding world.
In a certain fanfic, the portraits in Hogwarts come to life to scare the students straight. The portraits tell the students stories of the past, of wizards who misused their magic and faced terrible fates. Harry is initially skeptical but then realizes the value of these stories. This fanfiction is unique as it gives a new role to the portraits, which are usually just background elements in the original series.