(This is a short horror story I wrote on Reddit under some other name. I've slightly modified it.)
A row of moving ants is a fascinating thing to watch, if you are into such things. They never break the line, never overtake each other, never walk any faster or slower than is necessary, and make it virtually impossible for the untrained eye to identify the weakest link in the chain.
He observed them, in the darkness that his eyes had by now gotten used to. It had taken some effort for that to happen, but he was a patient man, and he had time.
In that dark dungeon, loneliness was not a problem. His entire professional life, his entire training and his singular focus had prepared him for long bouts of lonely missions.
Neither was the darkness an irritant for him. Darkness has a way of creeping up and engulfing your very being in a matter of minutes. As time passes, you feel yourself one with the blackness, your body just a corporeal extension of the eternal truth surrounding you. Your eyes adjust, your heart rate becomes normal, and you regain your sense of navigation. You become darkness, and darkness becomes you.
However, what you do lose is your sense of time. It is impossible to calculate the number of seconds passed. After a few hours, the lack of any form of light starts working its magic. Without sunlight to reset it everyday, the biological clock goes haywire, and you are unable to tell whether it is night, or day, or twilight, or July.
This loss of sense of time brings with it claustrophobia. You want to shout. You want to feel wind in your hair. You want to smell the gutters of your city. The fish market. The scent of your wife as she comes out of shower, towelling her wet hair. The putrid smell of gunpowder on the shooting range. The smell of disinfectant in the room where you had that fateful meeting with those two mysterious men . “Classified, sir. Not even your wife is allowed to know.” But if you are as motivated as he was, you let these thoughts assail you, but you never, ever succumb to claustrophobia.
He had been there for longer than he could judge. He had used this time well to perfect techniques of fighting back the now-regular assaults of claustrophobia. He had found that speaking out loudly helped. The regular clang of metal as they pushed his food tray was also a very welcome distraction.
He was unsure when the next welcome clang of metal would meet his ears, so he decided to talk. Talking also helped quell fears about losing his voice, or letting it go hoarse. He decided to introduce himself to the ants.
“My name is Major Kawasaki. I am a soldier of the Fifth Division of the Imperial Japanese Army, stationed in Hiroshima. I have volunteered for a top-secret project to determine a man’s ability to survive in extreme claustrophobic conditions, in complete darkness and without any human contact. As part of this experiment, I was locked in this soundproof, airtight, underground dungeon at 6:45 AM on the 4th of August, 1945. The air that you, my dear ants, and I breathe, is supplied via special vents. I think at least two or three days must have passed since I was locked here. I am waiting for food, but it seems to have taken an unusually large delay for it to arrive this time.”