AVPM-verse. I don't own Harry Potter or AVPM.
He sees Voldemort once.
Bellatrix is literally hanging off him, hands all over the Dark Lord's body.
He hates it.
He guesses that Voldemort is there to speak with the dementors. The Dark Lord's reign of evil wouldn't be complete without allying with the beings that suck all happiness from the world, after all.
He stares out into the corridor while hidden in the shadows of the corner of his cell, watches the two of them head towards the end of the hall. Bellatrix is quieter than usual. That's good. Hearing her voice in his nightmares is enough; hearing it in real life would be unbearable. He isn't looking at Bellatrix, though.
Voldemort's eyes are dull. He realizes that he'd only seen Voldemort's eyes for about five minutes, so maybe they'd always been that way. He'd never thought to do that mirror trick where you could see the back of your head while he and Voldemort were in the same body, so the only time he'd ever seen the Dark Lord's face was the night they danced. He wonders if Voldemort's gotten the chance to dance again since he'd been sent to Azkaban.
He first learned about Voldemort's love for dance one night while the rest of the castle slept. He wonders if Voldemort remembers the late-night conversations they had when one would have a nightmare and the other would pick up on it. Talking about whatever came to mind, until they could fall asleep again.
No one is there for him to talk to after his nightmares anymore, so he talks to himself. He supposes Voldemort would talk to Bellatrix about his nightmares, if he had any. Would Voldemort have nightmares? Hasn't he achieved his dream? He has a girlfriend, hundreds of followers, and domination over almost all of the Wizarding World. Voldemort should be the happiest man on Earth. So why does he look so...lifeless?
Quirrell supposes it's the dementors. They tend to have that effect on people.
He visits Azkaban once.
As soon as he steps into the prison, cold washes over his body. It's completely unexpected, like being pushed into an ice-cold lake. He's sure that much of the cold is guilt, though. Quirrell's in here somewhere -because of him- surrounded by this cold every day.
But he'd known that this would happen, right? He'd planned it from the beginning. Find some weakling who was unfortunate enough to be in the Forbidden Forest at the wrong time, leech off said weakling's soul for a year, separate using the potion, then take over the Wizarding World and become the most powerful being on Earth. All of the steps had been completed, so why did he feel so...lifeless?
It's the dementors, Voldemort tells himself. Of course.