Perhaps it is related to some old magic that he inherits. One day, when he is exploring an old, abandoned place like an ancient wizard's tower. There, he touches an old relic which activates this hidden ability. As soon as he touches it, he feels a strange connection with the shadows around him and realizes he can control them.
Perhaps he has a strange dream where he's in a world made entirely of shadows and he can manipulate them freely. When he wakes up, he starts to experiment and finds out that he can actually do the same in the real world. He might start with small things like making the shadow of a quill move on his desk, and gradually discovers the full extent of his power.
He could use his shadow - controlling ability to spy on the bad guys without being noticed. Just like he sends his shadow into their secret meetings, and the bad guys won't detect his presence at all.
It could be about Harry having the ability to control shadows in a fictional story. Maybe he uses this power for various purposes like solving mysteries or protecting his friends.
Well, 'consuming shadows' in Harry Potter fanfiction could be a title of a specific plotline. It might involve a character who is being haunted or chased by some sort of shadowy presence that is slowly taking over their life. Maybe it's related to the concept of the Dark Mark and how Voldemort's influence spreads like shadows consuming the wizarding world. It could also be a unique magical phenomenon created by an author for their fanfiction, like shadows that have a mind of their own and are 'consuming' everything in their path.
Well, in such a fanfiction, he might control space through his magic wand. Maybe he uses a special spell that he discovers or invents, which allows him to manipulate the fabric of space, like creating portals or warping distances.
One consequence could be that the wizarding world starts to view him with even more suspicion and fear. People are already afraid of dementors, and if Harry can control them, they might think he's becoming too powerful or even turning to the dark side.
It could also be due to his own inner strength and growth as a wizard. Harry has faced so many challenges and traumas throughout his life. His experiences might have awakened a latent power within him that allows him to control dementors. His strong willpower and determination, which have been developed over years of fighting against the dark forces, could be the key factor in this newfound ability.
It could be through some kind of inheritance. Perhaps he has some long - lost family connection that gives him this unique power. In the fanfiction, he might start noticing strange things happening around cold or icy elements, and then gradually realize that he can actually control them.