Hey Neon and Dono,
Great detective work everyone! Tbh, I was always a bit nervous that I made some of the killers too obvious (before seeing certain endings that is), so I'm glad that Neon described it as "non-hand holdy".
Also, I was very inspired by 999, in that you really didn't get a good picture of who the villain was until after experiencing several dead ends/endings. After seeing a few endings, the whole picture of this crew of murderers becomes clearer.
ABZI: Responsible for River's death and many other pornstars like/before him, mastermind behind all the killings in general. His scythe is the sharp weapon responsible for cleanly decapitating Timmy. Then Abzi has Evander killed, yes due to Soren's request, but it works out for Abzi's true goal of breaking Adam.
SOREN: Orchestrated Timmy's death, distracting Adam allowing The John's to clean up the corpse after Abzi and The John's torture and then decapitate him. Targets Evander later in the story. It's revealed , Soren revels beside Timmy's remains in the True End.
THE JOHNS: They participate in the killings of both Timmy and Tad.
HUNTER: Tosses Evander over the cliff at Abzi's behest.
And so, all 5 have their hands bloodied and why Adam allows vengeance in The True End.