Maybe the dolls are enchanted and they communicate with Harry. He might be the only one who can understand them, and he feels a special bond with them. For example, the dolls could be the spirits of past witches and wizards who are trapped in that form, and Harry, with his kind heart, tries to help them. Or perhaps Harry's love for dolls is seen as odd by his friends at Hogwarts, which leads to some interesting conflicts and character development as he defends his passion.
It could start with Harry inheriting a box of old, magical dolls from a relative he didn't know well. As he examines them, he realizes that each doll holds a piece of a forgotten family history. His love for the dolls drives him to uncover the secrets they hold. Along the way, he might face opposition from some in the wizarding community who think his focus on dolls is a distraction from more important matters. But Harry, being Harry, continues his quest, and through the dolls, he discovers a new aspect of magic and his own identity.
One possible plotline could be that Harry discovers a magical doll during one of his adventures. This doll has some special power or connection to his past, and his love for it grows as he tries to figure out its mystery. Another could be that he starts collecting dolls as a way to remember his lost loved ones, and the dolls become a source of comfort for him in the dangerous wizarding world.
One possible plotline could be that Harry discovers he has a half - brother he never knew about. Maybe his father had a relationship before he met Harry's mother, and this new character enters Harry's life. They initially have some conflicts due to jealousy or differences in upbringing, but over time, they come to love and support each other.
One possible plotline could be that Harry Potter discovers a new side of Fem Death that is not as menacing as she is often portrayed. Their relationship could start with a mutual curiosity and gradually turn into love as they get to know each other better.
One possible plotline could be that Petunia has a sudden realization of how unfairly she has treated Harry over the years and tries to make amends. She might start by secretly helping him with things around the house or protecting him from Dudley's bullying.
Well, a possible plotline might be that Harry saves Narcissa during a dangerous situation in the wizarding war. This act of heroism makes Narcissa see Harry in a new light, and he in turn is drawn to her vulnerability. As they interact more, their relationship blossoms. Or, it could be that they are brought together by some magical force or prophecy that they initially resist but eventually give in to their feelings.
I'm not sure specifically about 'Harry Potter loves dolls' fanfiction. However, there are many great Harry Potter fanfiction sites like Fanfiction.net and Archive of Our Own. You can search there for unique and creative stories. Maybe you'll find one that has this interesting concept.
One plotline could be Naruto being a transfer student at Hogwarts. He might struggle to adapt to the magic system while also showing off his ninja skills. Another could be Naruto teaming up with Harry Potter to fight a common enemy that threatens both the ninja world and the wizarding world.
One possible plotline could be Harry using his knowledge of the wizarding laws, which he learned through his years at Hogwarts and his experiences with the Ministry of Magic, to defend wrongly accused wizards in a wizarding court. Another could be him trying to reform the wizarding legal system which he might find full of loopholes and biases.
One possible plotline could be Harry trying to hide his merman identity while at Hogwarts. He might face challenges in the magical underwater areas of the school, like the lake. Another could be that he discovers his merman heritage and has to go on a journey to learn more about it and his new powers.
One possible plotline could be Harry being secretly trained by an unknown figure to become an assassin against the dark forces. He would have to hide this new identity from his friends at Hogwarts.
One possible plotline could be about the Weasley family trying to improve their financial situation. Maybe they come up with a new business idea in the wizarding world, like a magical product that becomes a huge success and changes their economic status. Another could be a story about how the Ministry of Magic regulates the financial system in the wizarding world, and there are some characters who try to manipulate or reform it.