Below, you'll see any text that was highlighted with comments from the reviewer.
It's that continued sense of tension and suspense throughout the piece which really caught my attention. From the outset, you personified 'suspicion' which was obviously really effective in setting the tone for the rest of it, and you gave out minuscule details as the story went on without revealing to the reader what the actual situation was. Although infuriating to read, it was really engaging and held my attention throughout because I was constantly analysing every sentence to pick up some hint as to the actual plot.
One of many things you're very strong at is succinct but really elegant description. Your descriptive sentences are the ones with the most individuality and uniqueness of voice - it's in them that you really experiment with style and tone. You don't just stick to the typical descriptions - 'black hair like a raven' - but use much more unique turns of phrase like the 'flat, dulling darkness'. This really helped to make the character seem real because he wasn't just a caricature. However, it might be useful if you could experiment with more ways of developing that character - does he have any more physical tics - for example he might have a habit of scratching his wrists or flexing his hands. You might also consider alluding a bit more to his personal life and relationships or past to add depth to his character.
I don't think I can suggest anything here - I obviously would have liked to know why he entered the room or how he got there but given that this is a novel excerpt I assume that I would have been given this information before were I actually reading the novel. I think what made this so incredibly strong was that it did sustain that mystery throughout, and expanding scenes and giving more detail might detract from that.
I don't really have a sense of setting from this. To an extent that's a good thing as it may add to that sense of isolation and mystery, however I think it could make this even stronger if you referred a bit more to the protagonist's surroundings. You can describe setting whilst retaining that tension and mystery, perhaps trying to indicate a sense of strain using the physical layout of the room or using some form of metaphor to show this. In terms of the senses you don't really refer to sound either - is it an eerie silence, or is there uneasy chatter? Equally, is the smell stale or sterile or sickly sweet? You could describe the texture of the chair and show your character's heightened awareness and attention to detail.
You have a really strong individual voice which I could really feel throughout this whole piece. Your writing style is so elegant and you aren't afraid to use more unconventional means of description. As I've said, it was so incredible that you managed to sustain such tension throughout this and I found it really enjoyable to read in that regard.
Well done - I really enjoyed reading this and look forward to reading more of your work in the future!