He might also face moral dilemmas. For instance, using this power to heal someone might seem noble, but if he uses it to harm or manipulate others, it would be a different story. He has to constantly struggle with the right way to use this power.
On the positive side, he can use it to protect Hogwarts. He could be like a living, breathing firewall against any fire - related attacks on the school. For instance, if the Dark Lord tries to set the castle ablaze, Harry can use his fire - controlling ability to counteract the flames and keep the students safe.
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.
One implication is the moral dilemma. Percy would have to decide when and how to use such a powerful and invasive ability.
One possible consequence is that it could change the dynamics of his battles. He could easily surprise his enemies and gain an upper hand in combat. For example, he could sneak up on opponents and land a powerful attack without them even realizing he was there.
Another consequence is that it would change his relationships within Hogwarts. His friends might be a bit scared or in awe of him having such a unique ability. Some students might be jealous. Teachers would also have to figure out how to deal with this. For instance, Professor McGonagall might be worried about how this new ability would affect Harry's studies and his place in the school. And Harry himself would have to learn to control this ability and not let it go to his head, as it could easily make him become overconfident or reckless.
Not being able to create control groups in the Starcraft 2 story can make the gameplay feel more restrictive. You might find it harder to adapt to different in - game situations. For instance, when facing a sudden rush of enemy units, in a normal game with control groups, you could quickly gather your defense units. But in the story, you have to do it in a more cumbersome way, which can be frustrating at times. It also changes the overall pacing of the game as you spend more time on unit selection rather than on actual strategic decision - making.
He could use it for various things. For example, he could create barriers of water to protect himself or others. He might also be able to manipulate the flow of liquids in a chemical experiment in the fanfiction world, leading to new discoveries. Another application could be in firefighting, where he can control any liquid and use it to extinguish fires more effectively.
A possible drawback is that it might require a great deal of concentration. Naruto is already dealing with a lot in combat, like using his various jutsu and strategizing. Adding blood control to the mix might overtax his mental resources, making him vulnerable to attacks. Also, if his enemies figure out his new ability, they could try to counter it by using techniques that disrupt blood - related manipulation, like creating strong chakra fields around their bodies to prevent him from accessing their blood.
Fanfiction can sometimes deviate a lot from the original story. It might be that the official creators or those in charge of the Harry Potter brand don't want the characters to be misrepresented in fan - made stories, so they restrict access to it for Harry or anyone in the context of that world. Another aspect is that some fanfiction may have a negative or unethical undertone, and to protect the integrity of the original story, access is prohibited.
One consequence could be that he becomes more curious and starts to explore places he shouldn't. Since he can be invisible, he might sneak into the restricted section of the library or into the teachers' lounge to uncover secrets. This could lead to him getting into trouble or finding out important information that changes the course of the story.