WARNING: The following contains spoilers for Link Click Episode 6, "Search of the Child", now streaming on Funimation.
In Episode 5 of Link Click, Cheng Xiaoshi's trust in Lu Guang is broken. Lu Guang knew which moment Cheng Xiaoshi would be time-traveling to and also knew that three people he was going to meet would inevitably die in an earthquake. He was aware there was nothing Cheng Xiaoshi could do about it, yet he gave him false hope and promised to help save Chen Xiao's mother.
In the end, Cheng Xiaoshi watched as Chen Xiao's mother sacrificed herself to save him and died before his eyes. This encounter causes a rift in Cheng Xiaoshi and Lu Guang's relationship, with the former unsure whether they can even work together again, let alone stay friends.
The days following the Chen Xiao mission are awkward, with Cheng Xiaoshi and Lu Guang each avoiding the other as much as possible. Qiao Ling confronts them but they remain tight-lipped. Eventually, she agrees to let them take a break from their time-traveling business. However, that break is short-lived when a police officer arrives with a father, Liang, who's desperate to find his son who went missing three years ago.
Liang explains that he and his wife had started a bubble tea business named after their son, Dou Dou, and weren't able to pay much attention when he wanted to play. With the customers demanding faster service and Dou Dou crying, it nearly overwhelmed his mother. Liang managed to distract their son by giving him his phone to watch his favorite cartoon. Dou Dou ran to a table outside, still in view of his parents while they quickly took orders. When they looked out again, Dou Dou was gone.
Liang spent much time and expenses trying to find Dou Dou but his wife, who reverted to a child-like state to cope with her grief and guilt, watched her son's favorite cartoon at home. The scene of Liang indulging his wife is reminiscent of what happened three years ago, except this time he isn't pushing her away like he did with Dou Dou. Liang begs the trio to help him but Cheng Xiaoshi echoes Lu Guang's words: the past cannot be changed and he would do well to look ahead to his future. Although Cheng Xiaoshi's words are harsh, it's obvious that he isn't going to turn away from someone who needs help.
So far, Qiao Ling hasn't taken much of a center stage in Link Click but we might be seeing more of her in the next few episodes. Three years ago, Qiao Ling had seen Dou Dou being led away by a stranger. At the time she did nothing and when she had been intercepted by Liang, she lied. Now she hopes to make up for that and help him find Dou Dou.
Lu Guang and Cheng Xiaoshi work together again without really resolving their issues. However, Lu Guang does reveal why he didn't tell the truth about Chen Xiao's case: although the words that Cheng Xiaoshi passed on to the three victims wouldn't change the past, it would bring comfort to those who are still alive. They have to keep looking forward, otherwise they would always remain stuck in the past and full of regret.
Whoever kidnapped Dou Dou took advantage of blind spots in the surveillance cameras. Surprisingly, when Cheng Xiaoshi travels back three years, he arrives as himself. He sees Dou Dou sitting by himself and witnesses the very moment when he's taken. He loses sight of the child but, as fate would have it, bumps right into Qiao Ling of the past.
Qiao Ling can't run from her past mistakes, which is why she wants to make up for it by helping Liang find Dou Dou. Although Lu Guang is often the one who reprimands Cheng Xiaoshi for being too stuck in the past, it may now be the former who can't escape from it. His choice back in Link Click Episode 1 -- to not tell Cheng Xiaoshi what happened to Emma -- will inevitably come back to bite him. A police officer in the past appears to be investigating a possible serial killer case, where Emma was one of the victims. The past and present are colliding to potentially devastating effects for everyone involved.