| Quote #1
[…] through the instrumentality of the Fiend Intemperance [I] had (I blush to confess it) experienced a radical alteration for the worse. (6)
So much for plain language, though readers in Poe's day would have been familiar with "the Fiend." This expression is a common way of representing addiction. The desire to drink takes on a life of it's own. It has "instrumentality."
| Quote #2
One night, returning home, much intoxicated, from one of my haunts about town, I fancied that the cat avoided my presence. (7)
What's interesting to us here is the word "fancied," which is similar to "imagined." The narrator is being tricky here. We can't tell if Pluto actually avoided him, or if the narrator imagined it. This moment seems significant when we consider the extreme affection of the second cat toward the narrator. Why doesn't that cat avoid him?
| Quote #3
My original soul seemed, at once, to take its flight from my body; and a more than fiendish malevolence, gin-nurtured, thrilled every fibre of my frame. (7)
In plain language, the narrator's "soul" leaves his body (he doesn't say where it goes). "Malevolence" is the desire to do evil. In the passage above, the desire to drink is shown as a fiend. Here, malevolence is even worse than a fiend. If what left the man's body was his "original soul." This malevolence might be a new one.