One possible plot twist could be that Harry has hidden magical abilities passed down from Regulus that no one expected. Maybe he can communicate with certain magical creatures in a unique way.
A plot twist could be that the truth about his parentage changes his relationship with the Malfoy family. Since Regulus had some connection to the Dark Arts initially, it might make the Malfoys see Harry in a different light, perhaps as a potential ally in a different way than in the original story.
Well, a really interesting plot twist could be related to the prophecy. If Harry is Regulus' son, it could change the interpretation of the prophecy completely. Instead of being the 'Chosen One' in the way we thought in the original series, it could be that his role as Regulus' son gives him a different mission. Maybe it has something to do with redeeming the Black family name and using the knowledge Regulus had about the Dark Lord to defeat him in a more unexpected way. This could also lead to a different relationship with Dumbledore, as Dumbledore might have known about Harry's true parentage all along and been guiding him differently.
Chapter 520, "Was Zheng Xun Replaced?!", is the clearest early answer because it turns Zheng Xun's situation into a concrete plot event. Early on, What did it mean that Jin Siyue had already given him all the shares?!.
Chapter 544, "I Shouldn't Have Stopped You from Pursuing Shang Shaojing Back Then", is the clearest early answer because it turns Bai Lu's situation into a concrete plot event.
Chapter 571, "Do You Know What Kind of Doctor is Standing in Front of You?", is the clearest early answer because the rescue effort creates visible on-page results. A useful checkpoint is the way the scene starts with You, you actually know about astronomy?" Jiang Yan lifted his chin,...
Chapter 469, "He Must Not Tolerate This Calamity", is the clearest early answer because it turns Children Palace's situation into a concrete plot event. The chapter turns that into something concrete by moving from There was no other choice, so Jiang Li and the others hastily turned...
Chapter 499, "Jiang, the Malicious Merchant is Online Again", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event.
Chapter 752, "The Sudden and Unforeseen Reversal", is the clearest early answer because it turns Shu Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on By what right do you arrest my son?!" Upon hearing the commotion, Mrs.
Chapter 493, "Affinity Only 50 Now?!", is the clearest early answer because it turns Zheng Xun's situation into a concrete plot event. Early on, You!" Shang Shaojing was so annoyed he gritted his teeth, "Jiang Yan,....
Chapter 532, "Little Lolita Beats Up Jungle Python?!", is the clearest early answer because it turns Zhou Xu's situation into a concrete plot event. The chapter turns that into something concrete by moving from Outside the cave, the four people grasped their weapons tightly and...
Chapter 791, "There's Actually a Suona?!", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event. It opens with The lights in the audience suddenly went out, and immediately, the...
Chapter 460, "Saving People", is the clearest early answer because it turns Yu Li's situation into a concrete plot event. It opens with [HAHAHAHAHAHAHA, Jiang Yan is impersonating me.] [At this moment, I... and closes on Dare to attack me in hiding?!.