Another plot could involve Percy exploring the powers that come with being the son of death. He might discover abilities like being able to communicate with the dead in a more profound way than before. Maybe he can even travel to the underworld more freely and has to face the consequences of interfering with the natural order there.
One interesting plot could be Percy's struggle with his new identity as the son of death. He might have to deal with being feared by others in the demigod community. For example, he could face challenges when trying to form alliances as other demigods are superstitious about his parentage.
A great plot would be Percy having to fight against an ancient evil that is somehow related to the concept of death. Since he is the son of death, he has a unique connection to this evil. He could be the only one who can truly understand its motives and weaknesses, but he also has to overcome his own self - doubt and the fear of his new powers.
Chapter 760, "Daoist, I've Long Heard of Your Great Reputation", is the clearest early answer because it turns Long Heard's situation into a concrete plot event.
Chapter 867, "Then what does our child count as?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.
Chapter 780, "There's Someone in Your Room!", is the clearest early answer because it turns Was Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Sister Li was a bit confused.
A practical answer is Chapter 17, because it turns the idea into a concrete scene. The chapter opens with Jiang Li glanced at Jiang Shixu, who was tense and anxious behind her, and..., adds pressure through That girl who puts on makeup like a ghost deserves to be called naturally..., and ends on.
Chapter 822, "The Yu Family Gave Too Much", is the clearest early answer because it turns Gave Too Much's situation into a concrete plot event. Early on, Jiang Li entered the reception hall, which was already quite crowded..
Chapter 816, "Don't Take Them Seriously", is the clearest early answer because it turns Mom's situation into a concrete plot event. The setup is Unexpectedly, they didn't cry or fuss;
Chapter 786, "Working at Chen'an?!", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event. The chapter turns that into something concrete by moving from When Jiang Li left Taiqi's office building, it was already getting...
Chapter 819, "Invitation", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from What Yu Li said is something these prominent families often do. to Lin Manru's studio also resumed work..
A practical answer is Chapter 1, because it turns the idea into a concrete scene. The chapter opens with Jiang Li, I'm warning you, don't set your sights on Yinwan anymore, or..., adds pressure through Coming to his senses, he also switched to a kindly smile, "Alright, girl,..., and ends on Yet.