Who might be the one to poison Harry Potter in fanfiction?

Maybe it's Dumbledore. In some fanfictions, Dumbledore is portrayed as a very father - like figure to Harry. Feeding Harry from a bottle could be a way of showing his deep care and protection for Harry in a different, more nurturing way than we usually see in the original series.

There's also a chance that Neville Longbottom could be involved in a cheating situation. He might have grown into a very different person in the fanfiction, and due to some complex emotional and social factors at Hogwarts, he cheats on his significant other. This would be quite a shock as Neville is usually seen as a very loyal character.

It could be related to a prophecy. The character was fated to be immune to poison for a greater purpose, like saving the wizarding world from a poison - based dark magic plot. So, they play a crucial role in the story without the fear of being poisoned like others.

One possible plot could be that a new, extremely powerful and irresistible poison is created by a dark wizard. The main characters, like Harry, Hermione, and Ron, have to find an antidote before it spreads and kills many students at Hogwarts.

It could be his loyal owl, Hedwig. She might be staying with him in the attic, providing comfort and also being a messenger for him when he needs to communicate with his friends outside.

Definitely Hermione and Ron. They are his closest friends and always by his side. Also, Neville would be a great addition. He has shown great courage in the original story. And of course, the members of the Order of the Phoenix like Sirius (if he were still alive in the fanfiction) and Lupin.

Well, in fanfiction, Neville Longbottom could be one of the visitors. He and Harry could exchange gardening tips as they explore the manor's gardens. Additionally, Dumbledore's portrait might be magically transported to Potter Manor, and he could offer his wisdom and guidance to Harry as he lives in the manor. And of course, Hagrid might come with some magical creatures to show Harry, adding more excitement to the manor.

One trait Harry might inherit is a strong sense of self - preservation. Poison Ivy is always looking out for herself in her own world, and Harry could have that same instinct. This could make him more cautious in dangerous situations. Also, he might inherit her ability to blend in with her surroundings. Since Poison Ivy can use plants to camouflage herself, Harry could have a natural knack for hiding or remaining undetected in the wizarding world. Maybe he could use magic in combination with this ability to stay out of harm's way more effectively.

His friends from Hogwarts, like Ron and Hermione, are likely to help. Ron could bring his family's practical knowledge of wizarding homes and Hermione would contribute with her extensive research skills.

Hermione would be a great help. Her vast knowledge of magic and books could provide the necessary information for building the planet, like the right spells and magical theories.