How are the Montresor family motto and coat of arms appropriate?

In the short story “The Cask of Amontillado,” Edgar Allan Poe develops a complex and unreliable narrator by using the Montresor family motto and coat of arms as symbols. The motto, “Nemo me impune lacessit” (“No one attacks me with impunity”), is displayed prominently on the Montresor family coat of arms, which features a serpent wrapped around a boot. The motto and the serpent symbolize Montresor's treacherous and vengeful nature. Additionally, Montresor's obsession with his family history and the glorification of his ancestors illustrate his pride and arrogance. These symbols and characteristics contribute to the development of Montresor as an unreliable narrator, as they cast doubt on his motives and his version of events.