A plot development could be that Harry, after being abandoned by the Dursleys, wanders into the Forbidden Forest near Hogwarts. There, he encounters centaurs who initially are wary of him but then see his plight. The centaurs could take him under their wing and teach him about nature magic and prophecy. Harry could then use this new knowledge to return to Hogwarts in a more confident and self - assured way, ready to face the challenges that await him, including dealing with those who knew about his situation with the Dursleys but did nothing to help.
Well, in this kind of fanfiction, it might be that Harry is adopted by a wizarding family from another country. This new family could introduce him to different magical cultures and traditions. He could learn spells and magical techniques that are not known in the British wizarding world. Also, he might start to explore his own identity without the shadow of the Dursleys. He could find out more about his parents from this new family's perspective and gain a new understanding of his place in the wizarding world.
One possible plot development could be that Harry discovers his magic earlier on his own due to the neglect. He might start exploring the wizarding world secretly, finding hidden magical artifacts in the neighborhood. Another could be that he forms an unexpected alliance with the local magical creatures that sense his isolation. Maybe he even starts teaching himself basic spells from an old, dusty spellbook he finds in the attic.
Another plot development could be that the Dursleys try to keep Harry's magic a secret from the wizarding world, fearing they will lose him. But as Harry grows older, he starts to find ways to reach out to the magical community on his own, like making friends with a stray magical creature that finds its way into the Dursleys' backyard.
One possible plot development could be Harry finding a new magical family or community that accepts him wholeheartedly. Maybe he discovers a hidden magical society that has been observing him at the Dursleys and now offers him a real home and proper magical training.
He might become more independent. Without the Dursleys, Harry would have to fend for himself. He could start to discover his true powers faster as he no longer has to hide his magic in the Dursley household. For example, he could practice magic freely and develop his skills more quickly.
One possible plotline could be Harry finding a new family among the magical creatures. For example, he might be taken in by a friendly centaur herd who teach him their ways of magic and survival. Another could be Harry being found by a secret group of wizards who are against the Dursleys' cruel treatment and they help him develop his magic in a more positive and nurturing environment. And there could also be a plot where Harry discovers a hidden magical power within himself as a result of the abandonment, like the ability to communicate with the spirits of Hogwarts, which then guides him on a new path to face Voldemort.
In certain fanfictions of this type, Harry could be found by a powerful but reclusive wizard. This wizard decides to mentor Harry in the ways of ancient and lost magics. Harry then uses this knowledge to not only become a very powerful wizard but also to change the wizarding world's view on things like blood purity. He may also go on a journey to find out why the Dursleys abandoned him and in the process, uncover some dark secrets about his family that had been long buried.
One possible plot development could be that Harry discovers new magical abilities or knowledge within the Greengrass family. Maybe they have a unique magical heritage that helps him in his fight against Voldemort.
In this fanfiction, perhaps Harry is kidnapped by the Order because they think he's being influenced by dark forces. As the story unfolds, he could start to understand their reasons while also uncovering a traitor within the Order who wants to harm him for real. Or, he might use his skills to turn the situation around and make the Order see that they were wrong to kidnap him in the first place. He could then lead them in a new direction against Voldemort.
In the 'Lockhart Kidnaps Harry Fanfiction', it could be that Lockhart is being controlled by a dark force without his knowledge. This dark force wants Harry for some evil purpose, like using his connection to Voldemort to resurrect the Dark Lord. Lockhart, being the vain and easily manipulated character he is, is just a tool in this scheme. He might initially think he's in control, but as the story progresses, he realizes he's in way over his head.
Another development could be that the king's courtship is part of a larger political plot. Harry discovers that the king has ulterior motives, like using Harry to gain influence over the wizarding world. Harry then has to figure out how to expose the king's true intentions without causing chaos in the magical community.