One reason could be that he's desperate for any form of guidance. After all the chaos he's been through, divination might seem like a way to get some answers about the future. It's like grasping at straws, but it could be important to him.
Maybe he has a new mentor in the fanfic who is really into divination and convinces him of its value. This mentor could show Harry how divination can be used not just for predicting the future but also for understanding himself and the magical world around him better. So, he starts to take it seriously.
In the fanfic, there could be a prophecy that is related to divination. Harry, knowing how important prophecies can be in his life, decides to take divination seriously in order to fully understand this new prophecy. He believes that by studying divination, he can figure out how to either fulfill the prophecy in the best way or avoid a negative outcome if it's a dangerous one.
Chapter 201, "Wuyuan Garrison, Cold Marrow Iron", is the clearest early answer because the buildup finally cashes out in a real clash. The setup is Because as he spoke, he was constantly observing the reaction of that..., but the pressure keeps building through Just as expected, the one-eyed Great Xia Leader and the eight people....
Chapter 306, "Rebel Collaborators, Chaos and Opportunism, Long Mountain Changes Hands", is the clearest early answer because it turns Li Tiancheng's situation into a concrete plot event. The chapter gives readers a real answer by opening on Hu Zi has been captured by Li Tiancheng. and ending on The Cloud Dragon Army should be resting below now, including guarding....
Chapter 223, "Outbreak of Battle, Breaking the Siege, Honored Guest", is the clearest early answer because the buildup finally cashes out in a real clash. It opens with Hou Hu still clutched his neck with his right hand, and in a panic,... and closes on Out of nowhere, someone appeared to save him.. The key payoff is that the danger stops being abstract and the conflict around Long Mountain becomes immediate, forcing the surrounding cast to react under pressure.
Chapter 195, "Jade Bone, Conclusion, Cultivation Dilemma", is the clearest early answer because it turns Arrow Bamboo Forest's situation into a concrete plot event. The chapter gives readers a real answer by opening on With such a small price to pay, to understand a part of the power of... and ending on Calculating across the years, how many have there been in total?.
Chapter 222, "Indecision, Blood Guard Army, Sudden Turn of Events", is the clearest early answer because it turns Li Xuanyan's situation into a concrete plot event. The chapter turns that into something concrete by moving from As it turns out, during this operation to eliminate disobedient camps... to Great Master, Xiling Camp has no rebellious intentions; it was only....
Chapter 262, "Garrison Candidates, Martial Arts Enthusiasm, and the Eve of a Breakthrough Tide", is the clearest early answer because Xia Hong finally turns buildup into a real advancement. The chapter turns that into something concrete by moving from The majestic golden dome; Blue leather blankets covering the entire... to Once these two agree to join Great Xia, the other two wouldn't be an....
Chapter 268, "Advancement, Warnings, and Inspections", is the clearest early answer because Hunting Department finally turns buildup into a real advancement. It opens with Big brother, the conditions at Wushuang aren't great, but over at Xia... and closes on Especially after this round of Longyou war, probably from having.... The key payoff is that it turns Hunting Department's growth into a concrete upgrade step and sets up the next payoff in the power growth storyline linked to Xia Chuan.
Chapter 212, "Dispute—Can't Hold It?", is the clearest early answer because it turns Hong Yu's situation into a concrete plot event. Early on, After two years in the Beehive, Luo Ming hadn't attained elite.... By the end, Big brother, what about Hong Yu?" Just as Luo Ming was about to....
Chapter 218, "Departure, Sending a Letter, Killing", is the clearest early answer because the violence around Pingxi Plain becomes final instead of hypothetical. A useful checkpoint is the way the scene starts with Long Mountain is located more than fifty kilometers to the west of... and follows through with Just follow Chen Yingyuan to see what's going on, and once we reach....
Chapter 207, "Reforming Corvée Labor, Changes in the First Year [Happy New Year!!!]", is the clearest early answer because it turns Hefeng Camp's situation into a concrete plot event. It opens with On the southern side of the Great Xia Valley, there is a giant... and closes on Brother, how long have you been in Great Xia?.