This was a fun story. When he asked, "Is Balky with him?" I laughed audibly. Yes, I could see it coming a mile away, but it was done so well written and read that I enjoyed it anyway. I liked the descriptions of the environment, including the fetid smells, yellowed ceiling, well-maintained plants, etc.
The story ends too quickly once she finds out who Pepé is, though. I would have liked more suspense. Think about it: You are stuck in an A/C vent with a huge snake that considers you dinner. The only way to get away from the snake is to go backwards up a sharp incline wearing flannel clothing that slides on the metal. At the top of the incline is a heavy, iron grate that is drilled in place. You've just watched the snake eat a dog and you know you're next. What a predicament! I would have liked her terror to last a bit longer. She could try to squirm back up the vent or try in vain to pound out one of the walls of the vent. It seems like a waste to spend so much time building up to a moment that only lasts a few seconds.