Well, one possible plot development could be that Harry has to hide his new status as an Obscurial from his friends at Hogwarts for fear of being ostracized or worse. Another could be that Voldemort somehow discovers Harry's new condition and tries to use it to his advantage, perhaps by trying to manipulate the Obscurial power within Harry. Maybe Harry has to learn to control this new, dangerous power on his own as he can't trust Dumbledore or the other teachers with this secret at first.
In this fanfiction, it's likely that Harry's newfound lordship at age 7 will have a significant impact on his relationship with the Dursleys. They might be even more intimidated by him, or perhaps they try to take advantage of his new status in some way. Harry, on the other hand, could use his new power to free himself from their abuse and start living a more independent life within the wizarding world. He may also discover new magical abilities or artifacts associated with his Potter heritage that help him in his journey.
If Harry Potter becomes an obscurial in fanfiction, the story could take a very different turn. He might not be as eager to attend Hogwarts as he was originally. The Dursleys might have an even worse time with him because his obscurial powers could lash out. At Hogwarts, teachers would be extremely concerned. Snape, for instance, might be even more critical of him, seeing him as a potential danger. And Harry would have to learn to control this new and dangerous aspect of himself.
In the fanfiction, it could be that Harry faces opposition from some powerful wizarding families who don't want him as high king. They might try to undermine his rule through various means such as spreading false rumors or plotting against him. Harry would then have to prove himself worthy and strong enough to maintain his position.
One possible plot development could be that Harry uses his new status as Lord Peverell to gain access to ancient magic and knowledge. He might then use this to defeat Voldemort in a more powerful and unexpected way.
Well, one possible plot development could be that Harry starts to question the existing power structures in the wizarding world. Maybe he feels that the so - called good side has its own flaws and secrets. He might then begin to amass his own power, secretly at first, perhaps by seeking out dark magic spells that have been long forgotten. He could start to gather followers who are also disillusioned with the status quo.
Perhaps during the rebuilding, Harry has to deal with various magical creatures that have made the ruins of Potter Manor their home. He might have to find a way to relocate them without harming them. Also, he could be visited by friends from Hogwarts who offer their help and in the process, there are some interesting interactions and exchanges of magic knowledge.
In some cases, it could be other dark wizards or witches who are envious of Harry's new power. They might want to steal his Obscurial power for themselves or use it to gain dominance in the dark wizarding underworld. These antagonists might be minor characters in the original series but could be developed more in the fanfiction to create new and interesting conflicts for Harry.
In some of these fanfictions, Harry might start exploring the dark art of necromancy secretly. He could be driven by a desire to bring back his lost loved ones, like his parents. This often leads to him having to hide his newfound interest from his friends at Hogwarts, creating a lot of internal conflict as he struggles between what he knows is right and his longing for his family.
Often, Harry as a lord may have to deal with the political side of the wizarding world. He might face opposition from the old pure - blood families who don't want a 'half - blood' lord to have so much power. So, there could be a lot of intrigue and power struggles in the story.
One possible plot development could be that Harry has to face a lot more internal conflict. He would be associated with a house that his friends might view with suspicion. Also, he might discover new magical abilities or powers that are related to the Slytherin heritage.