Harry would likely be very conflicted. He has seen a lot of death and has always fought against dark magic. The Death Note's power to kill just by writing a name is something that goes against his values. He would probably try to keep it away from others and might even consider destroying it.
Dumbledore would be extremely cautious. He has great wisdom and would understand the implications of such a powerful object. He would likely study it carefully, try to understand its origin and the rules that govern it. He would also be very concerned about the moral and ethical implications for those who use it and those who are affected by it. His main goal would be to keep it out of the wrong hands and to prevent chaos in the wizarding world.
Chapter 74, "Ordinary People", 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 Having seen Jiang Li's ID before, he knew that this person named...
Chapter 339, "Today's Windfall Luck!", is the clearest early answer because it turns Miss Jiang's situation into a concrete plot event. The chapter gives readers a real answer by opening on The models had already stopped their runway walk when they heard the...
Chapter 510, "The Fake Young Master", is the clearest early answer because it turns Gu Group's situation into a concrete plot event.
Chapter 181, "Are All the Weibo Followers Police?", is the clearest early answer because it turns West District Police's situation into a concrete plot event.
Chapter 243, "How Could It Be Her?!", is the clearest early answer because it turns Southwest Plateau Airport's situation into a concrete plot event. Early on, Hahaha, the young master's face has gone white, but I got a scare....
Chapter 183, "Sacrifice Oneself, Break Them Up!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Seeing that he held a blue ball identical to Su Yinwan's, Jiang Yan...
Chapter 349, "Everyone Who Went Out to Dinner that Night Got Poisoned!", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. It opens with The news quickly reached Ye Chu. and closes on Let alone the situation with the Gu Family....
Chapter 298, "Turning the World Upside Down", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event. Early on, Grandfather, I, I can testify, everything Sister said is true." Right....
Chapter 112, "The Strange "Team Spirit" Appears", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter turns that into something concrete by moving from These five people are supposed to be at odds.
Chapter 283, "You Will Never Understand the Importance of Family!", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event.