English borrowed aegis from Latin, but the word ultimately comes from the Greek noun aigís, meaning “goatskin.” In ancient Greek mythology, an aegis was something that offered physical protection.

The spelling "Aegis" as appears in the original Japanese region titles is technically a misspelling of アイギス in English. The correct spelling, "Aigis" is the acceptable rendering of the original Greek. In fact, Aigis is the preferred spelling of the proper noun by contemporary academic standards.

The Answer Orpheus becomes Aigis' Persona. During a heated battle against Metis, Aigis summons Athena. At the same time, she awakens to a new Persona and Athena metamorphosed into Orpheus.

It is revealed that Aegis' ability to feel these emotions is because of Yuu, who gave her her Papillion Heart and intended for Aegis to be like a normal human being.