Sometimes we overthink things way, way too much that we ignore all the hints in front of us. Here is the long winded solution and story for the “cipher” of chapter 2
Initial clues from randomness
Clue 1
Clue 2
Clue 3
Socks assistance finding the original hint (Source C1D)
Solution
Now to get into the actual solving, due to randomness confirming the source from the first chapter we can guess that the second source would be something similar to that. The only one that first the bill would be source C2D, which is also a text conversation between Serena and Troy. (At first I was mislead that it could have been C2C since randomness said it was his favorite source, but that didn’t really lead anywhere.)
Chapter 2 Cipher source (C2D)
ITEM D: Serena’s message history with Troy.
C2D
Serena:
Tomorrow? The park down the road.
Troy:
Hi
I could make it tomorrow.
So how are you doing? Feeling better?
Serena:
I’m great! Though I’ve got to go now, so bye!
See you about.
Troy:
No Serena wait a sec
Serena:
Oh?
Troy are you still there?
Troy:
Mhm, just wanted to ask something. Have you like
You know felt like something’s off recently?
Serena:
Possibly? What do you mean by ‘off’?
Troy:
As though the world keeps changing in ways it shouldn’t, unnatural ways?
Serena:
I do have something, I wasn’t going to tell anyone
Nevermind don’t worry about it, it probably was nothing.
Troy:
Tell me, please
Serena:
Oh well it won’t hurt. Remember earlier walking back from school? I thought I saw a building which looked like it was on frie
*Fire
Eventually I convinced myself it was just the light or something, it couldn’t have been real especially because I thought the fire was bright white.
Troy:
Eerie, we can talk more tomorrow. I’ve just got something to do.
Love you.

(Admittedly “Cipher” is a bit far for this one, but it’s a hidden message)
At first I thought it could have been some sort of matching between the two sources considering the weird spacing in source C1D and that randomness has stated it’s not exactly a cipher, but that only made nonsensical sentences and left me at another dead end. However, Randomness placed the final nail in the coffin when he gave this final hint:
Could it be? There was a sentence hidden on the first letter of each message? Let’s check with our first source, C1D.
Solving C1D for a hint
First we remove the lines of “Serena:” and “You:” since it doesn’t contribute to the message
C1D
ITEM D: Troy’s messages with Serena
All good after today?
Cold.
Really? I meant the accident.
Oh, yeah I’m good. It doesn’t hurt anymore.
So do you want to go somewhere together after school tomorrow?
Troy?
I’d love to!
Cool. See you.Goodnight Serena.
Goodnight Troy <3.
Then by using the letters of each word we get “ACROSTIC GG”
A quick google search reveals that acrostic, or acrostic poems are “poems or other word composition in which the first letter of each new line (or paragraph, or other recurring feature in the text) spells out a word, message or the alphabet.”
This confirms that reading the first letter of each line will yield a hidden message.
Applying the hint to source C2D
Now we apply the same logic to the other message source,
ITEM D: Serena’s message history with Troy.
C2DTomorrow? The park down the road.
Hi
I could make it tomorrow.
So how are you doing? Feeling better?I’m great! Though I’ve got to go now, so bye!
See you about.No Serena wait a sec
Oh?
Troy are you still there?Mhm, just wanted to ask something. Have you like
You know felt like something’s off recently?Possibly? What do you mean by ‘off’?
As though the world keeps changing in ways it shouldn’t, unnatural ways?
I do have something, I wasn’t going to tell anyone
Nevermind don’t worry about it, it probably was nothing.Tell me, please
Oh well it won’t hurt. Remember earlier walking back from school? I thought I saw a building which looked like it was on frie*Fire
Eventually I convinced myself it was just the light or something, it couldn’t have been real especially because I thought the fire was bright white.
Eerie, we can talk more tomorrow. I’ve just got something to do.
Love you.
Putting all that together, we get the final hidden message of “This is not my pain to feel”
What a rabbit hole