Perhaps an enemy from a rival group. They might see Sakura as a threat to their plans, so they poison her to get her out of the way. Another possibility is a character who has been secretly harboring a grudge against her for a long time, and finally decides to take action by poisoning her.
In a 'sakura gets poisoned' fanfiction, she might first start to feel unwell, like having dizziness and weakness. Her friends could then notice the strange symptoms and start to search for a cure.
It could be Morgana. She has been known to be an antagonist and has a vendetta against Camelot and those associated with it. Poisoning Merlin would be a way to weaken Arthur's most powerful ally.
Well, it could be Harry who punches Ron. Maybe Ron betrays Harry's trust in some way, like perhaps revealing a secret of Harry's to the wrong people. And Harry, being really angry about it, punches him in a moment of rage.
Well, it's simple. In the fanfiction world, Ron is sometimes portrayed as jealous because Harry is the famous 'Chosen One' and Hermione is super - intelligent. When they spend time together, Ron may think they are forming a clique without him. He's also a bit insecure, and seeing Harry and Hermione's camaraderie might make him fear that he's not as integral to their group as he wants to be. So, that jealousy pops up.
In this 'naruto gets poisoned fanfiction', Naruto could also try to fight the poison using his own chakra. He might enter a state of inner struggle where he has to battle the effects of the poison on his body while still trying to protect the village. His Nine - Tails chakra could play a role, either helping him resist the poison or making the situation more complicated if it reacts badly with the poison.
Sakura would be a likely candidate. As a skilled medical ninja, she has the knowledge and ability to diagnose the poison and attempt to create an antidote.
Well, he could experience intense pain and weakness. Depending on the type of poison, it might affect his connection to his father Poseidon. Maybe he'd be unable to communicate with sea creatures or draw strength from the ocean as he usually does. His friends would be in a panic. They'd probably split up, with some staying to take care of Percy while others go on a quest to find the source of the poison and a cure. Chiron at Camp Half - Blood would also be involved, providing what knowledge he has about such poisons.
If Harry Potter gets poisoned in fanfiction, it could lead to some really interesting plot twists. His magical powers might be affected. He could start having strange visions or lose some of his abilities temporarily. Dumbledore or other teachers might get involved in a big way to figure out who poisoned him. And the whole Hogwarts community could be in an uproar, with students trying to find out the truth and protect Harry from any further harm.
In these fanfictions, Ron's jealousy is portrayed in various ways. Sometimes he'll try to interfere with Harry and Hermione's time together. He might create small misunderstandings between them on purpose. Other times, he'll show his jealousy more subtly, like by looking sad or disappointed when they share a private joke or moment. His body language can also give it away, like crossing his arms and frowning when they are being friendly with each other.