"Within the wall thus exposed by the displacing of the bones, we perceived a still interior crypt or recess... for no especial use..." (5) The secret room is the grave for Fortunado.
Gothic Protagonist: Emotionally cut off from others
"You are rich, respected, admired, beloved; you are happy, as once I was."
"...I heard the furious vibrations of the chain. The noise lasted for several minutes, during which, that i might hearken to it with the more satisfaction, I ceased my labors and sat down upon the bones."(6) Montresor is stopping his work just to enjoy listening to someone suffer.
Decay: a formerly great family
"The Montresors were a great and numerous family."
"Nemo me impune lacessit. (latin-No one attacks me without impunity."(4) Montresor says that anyone that attacks him will somehow get punished.
"You are rich, respected, admired, beloved; you are happy, as once I was."(3) Montresor is jealous of Fortunado.
"The Montresors, I replied, were a great and numerous family."(3) Montresors family was once powerful, but is now weak.
"These vaults are extensive"
"...the intoxication of Fortunado had in a great measure worn off."(6) Fortunado somehow went from completely drunk to sober in a few minutes, which is impossible.