Who?

Noah was trying very hard to remember the place where he had seen the painting. He couldn't remember the place, no matter how hard he tried. He felt like the painting was the key to something big.
He was lost in his thoughts, when all of a sudden, the ring which he had been wearing started to glow, a red glow initially which turned into dark brown and then finally, smoke like glow, but it was hardly a glow, it was more of a depressing light, it gave off scary vibes.
Woojin noticed the scare and panic on Noah's face, 'Noah, You should take that ring off, give it to me.' Noah took the ring off and handed to Woojin and finally he felt relieved.
Noah suddenly realised something, all this while, Robin, who was with them, hadn't spoken a single word. He became worried because whenever Noah is scared, Robin had always been the first one to comfort him. Noah turned to take a look at him, but he saw that Robin wasn't even there in the moment, he was lost in his own thoughts, 'Robin, what're you thinking, you have been silent ever since we started from Woojin's house.' Robin was startled by Noah's voice, as if he wasn't even aware of Noah's presence. Robin was about to speak when Woojin called them out, 'Noah, Robin, come here and see this.' They went there, but Noah was left bewildered upon seeing what was going on, 'This ring, as soon as I showered white light upon it, it changed it's smoke colour and it smelt like burning of wood, but when I showered dark light upon it, it started giving off the foul smell of fibre burning like plastic burning and when no light is showered upon it, it just gives off dark, smoke like light without any odour.' Woojin informed them.
Noah was pondering upon this weird behaviour of this even weirder ring. Suddenly, he had an epiphany, he remembered where he had seen the painting. 'Robin, you remember that picture you had shown me, the picture of your old bedroom upstairs and I said that the painting in the background is even weirder. The painting on the right side of the passage ahead is the same painting.' Noah told Robin. 'It is not the same painting, it might be that it's another copy of that painting.' Robin said. But Noah still thought that it was the same, because now he could remember the layout of the frame, it was of the same shape.
They exited that room and continued forward when he observed the painting carefully, he was sure that it was the same painting as that in Robin's photograph. The setting, position, frame, everything was the same. He then remembered that Robin's house was only one lane apart, in fact this house would be bordering his home. Suddenly Woojin's facial expression changed from sad to that of having an epiphany. 'I know who is behind all these events, it's very obvious and the complete, unfiltered truth will be revealed.' 'Who is it?' Noah asked