JITD Theory: The Final Case will be about Pei Su
Before Episode 26 airs, I want to speculate on something. I haven't read Mo Du/Silent Reading yet - so please no spoilers only theorising. But I think Pei Su is going to try and bait Janitor into choosing him as the next Apath to target/reveal
In episode 25, Pei Su points out that the goal of the Janitor's organisation is to expose Apaths with deep roots in Xinzhou by exposing Sunshine Foundation's criminal Apaths. We know that Pei Su's dad was originally a member/founder/sponsor of the Sunshine Fund and one of the most extreme types of psychopath who tried to raise Pei Su the same way.
Luo Weizhao says that it's almost time for the Janitor to reveal his true intentions. When they sit at the desk, Pei Su rubs his forehead as if he's thinking about something very hard.
He then tells Luo Weizhao that he has a lead coming in a few days. I'm wondering if the plan is for Pei Su to pretend to side with the Sunshine Foundation and then try and make the Janitor target him to drag both organisations into the open. In episode 21, Pei Su revealed that the Sunshine Foundation had tried to contact him subtly but he had thus far avoided them. He also thinks that when enough sponsors have been unmasked by the Janitor, they will come to him for emergency financing.
We also know that Pei Su has his own plan going in the works that he hinted to Luo Weizhao right at the end of episode 25. In episode 24, he seemed to show Du Jia something inside the car (perhaps instructions for an as yet unknown task)
But we were in Luo Weizhao's POV looking into the car so we don't see it.
And this line could be just Pei Su reemphasising his previous points to Du Jia in their heart to heart conversation, but could also be him making sure Du Jia understands the next part of his plan. Given that both Pei Su and Du Jia seemingly look down at something, that's my guess. Additionally, Pei Su gives a confirming nod to Du Jia (unseen by Weizhao) as he gets in his car that again could be read as a farewell kind of nod but could also be a - you know what to do - kind of thing.
A little later in episode 24, he makes a phone call after making sure Luo Weizhao has left the house. We don't know who to or what is discussed, but ominous music plays in the background. What if this was part of Pei Su trying to seem as tough he is ready to play along with the Sunshine Foundation and that's who he was contacting?
Also, as much as Pei Su says he is the perfect candidate for recruitment by the Sunshine Foundation, he is also the perfect target for the Janitor IF he was a psychopathic Apath; a well established Apath in the perfect place to cause corruption and manipulate the SID (something Pei Su even points out himself - though in relation to the idea of him being the most likely suspect for the Janitor's identity in episode 21)
Which is something even Luo Weizhao was suspicious of up until episode 21. Pei Su was literally at the centre of his suspect board that he made in episode 15.
Now, as the audience, we know that Pei Su isn't involved in either organization. We also know that the Janitor is somehow aware that Pei Su is part of the 1.3% of Apaths. He says as much in an earlier episode that it would be great if Pei Su joined them but he has flawed genetics. (I tried to find the screenshot but I couldn't remember the episode number.)
Additionally, not all of Pei Su and his family mysteries have been uncovered yet. The Janitor already used a 'Wuthering Heights' reference to pinpoint Pei Su's father meaning he knows how abusive Pei Su's home life was as a child. But there are still flashes of an unknown incident happening in the basement when Pei Su was younger and his mother was still alive.
So what if the last case of Justice in the Dark is centred around uncovering Pei Su's mysteries. Pei Su pretends to be one of the Sunshine Foundation's Apath criminals by being available as a sponsor when they need money (to gain access to their inner circle) which then bring the Janitor in to focus on Pei Su and try and expose him as a dangerous Apath thereby revealing the final mysteries around Pei Su and his past?
Let me know what you think! Like I said, no book spoilers please, this is just some fun theorising before the final 5 episodes air!
