What could be the possible reasons in fanfiction for Harry Potter coughing blood?

Another possibility is internal injuries from a battle. Fanfiction often has intense battles that are not part of the original story. Harry could have been hit by a powerful spell during a fight that caused internal damage, which then makes him cough up blood.

It could be due to a dark curse or spell. Maybe he was attacked by a powerful dark wizard using a forbidden spell that affects his internal organs and causes bleeding.

Maybe he was poisoned. There are many villains in the Naruto world who use poison. If Naruto was poisoned during a fight or an ambush, it could lead to him coughing blood as his body tries to fight off the toxins. Just like how Sasuke was once poisoned and had to be treated.

It could be a dark magic curse. Maybe some enemy has cast a spell on Harry that is slowly sapping his health, leading to him coughing blood.

One reason could be a hidden disease or affliction that is unique to the fanfiction world he is in. It could be something that has been passed down in his family magically. Or perhaps he has been in a situation where he was exposed to a harmful magical energy source for too long. This continuous exposure could gradually damage his body and result in coughing up blood. For instance, if he was trapped near a leaking magical artifact that emits harmful rays.

One reason could be overusing his chakra. In Naruto's world, chakra is like life energy. If he overexerts himself and drains too much chakra, it can cause internal damage, leading to coughing up blood. For example, when he was training intensively or during a tough battle where he pushed his limits.

It could be a new dark wizard. There are always new threats emerging in the fanfiction world. This new dark wizard might have a vendetta against Harry and uses a special spell or potion to make him cough up blood.

One reason could be to gain power. In fanfiction, the author might want to show Harry in a situation where he needs a significant boost in power and blood magic seems like a way to achieve that. Another reason could be for revenge. If he's been wronged greatly, he might turn to blood magic as a more extreme form of retaliation.

Well, one reason could be that he was poisoned. In the world of Harry Potter, there are many poisonous substances. A fanfic writer might create a scenario where Harry is unknowingly poisoned, and this causes him to throw up blood as his body tries to fight off the toxin. Another possibility is that he has some sort of internal injury from a fight. If he got hit by a powerful spell or a physical attack during a battle, it could lead to internal bleeding which results in throwing up blood.

One interesting fanfiction could be 'The Darkening Plague' where Harry's coughing blood is a sign of a dark curse spreading in Hogwarts. It has a great plot that weaves mystery and magic.