It could be that he has been wronged by the wizarding society. So, in a form of rebellion, he decides to become a thief. He might steal from those who he thinks are corrupt or unfair. For example, if the Ministry of Magic has been unjust to him or his loved ones, he could target them or their allies. Another possibility is that he is influenced by a powerful and devious character who convinces him that stealing is a way to gain power or freedom.
He might become more sneaky and calculating. Since he's a thief now, he would have to be good at hiding his actions and planning his 'heists'. His moral compass might also shift a bit as stealing isn't exactly an ethical behavior in the normal wizarding world.
In some fanfictions, Harry Potter could potentially be depicted as a 'good thief' in a rather unorthodox sense. For example, if he's stealing something for a noble cause like stealing a powerful artifact from a dark wizard to prevent it from being misused. But in the original canon, he is not a thief.
One popular 'Harry Potter' thief fanfiction could be about a character stealing magical artifacts from Hogwarts. Maybe it's a student who feels wronged by the school system and decides to take matters into their own hands in a rather unethical way. For example, they might steal a powerful potion ingredient that was going to be used for a very important experiment in Potions class, which then causes chaos as the teacher tries to find out who did it.
There's no official information indicating that Harry Potter has read The Lightning Thief fanfiction. Harry Potter exists in his own fictional universe, and while fans might create crossovers in fanfiction, within the original canon, there's no such scenario.
A Harry Potter thief friend fanfiction could focus on a Muggle - born thief who accidentally discovers the wizarding world. They befriend Harry and get drawn into the magical chaos. Their thieving skills, which they developed on the streets in the Muggle world, are now put to use in a different context. For instance, they steal a key from a Death Eater's pocket during a battle that unlocks a hidden chamber where a powerful weapon against Voldemort is stored.
In the Harry Potter fanfiction, the 'thief of time' could be a character that has been overlooked or underestimated. It could be a young wizard who discovers a powerful but dangerous magic related to time. He might not fully understand the consequences of his actions and accidentally becomes the 'thief of time'. Or it could be a shape - shifter who uses different forms to steal time without being detected easily. They could be stealing time from important magical ceremonies or from the lives of key characters in the story.
In this Harry Potter fanfiction titled 'the thief of time', it could be centered around a mystery. The 'thief of time' might be a mysterious figure that no one can quite figure out. It could involve the characters like Harry, Hermione, and Ron trying to solve the mystery of who this thief is. They might have to explore different time periods in the wizarding history, using spells like the Time - Turner, to find clues and stop the thief from causing more chaos in the world of magic.
There are indeed. In certain Harry Potter fanfictions, a thief could be a new character introduced into the story. They might steal rare potions ingredients from the Hogwarts stores. This would then lead to a mystery within the school as the students and teachers try to figure out who the thief is. It can add a whole new layer of intrigue to the familiar Hogwarts setting.
One idea could be that Harry discovers a hidden centaur community in the Forbidden Forest. He's initially scared but soon realizes they have a deep connection to magic that Hogwarts has not taught. He starts learning from them, about their archery skills and how they communicate with nature.