The Roman God That Inspired Quirrell In Harry Potter
In "Harry Potter and the Sorcerer's Stone," Lord Voldemort seeks to acquire the titular stone to secure his rebirth and immortality. He's aided and abetted by Professor Quirrell, an ambitious young man who taught Defense Against the Dark Arts at Hogwarts school in the first entry in the series. Quirrell seemed timid, but was actually sustaining Voldemort, who shared his body as another face on the back of Quirrell's head, concealed beneath a turban. The two-faced nature of the character took inspiration from a curious god from ancient Roman mythology.
According to Britannica, Janus was a deity of beginnings, endings, archways, and doorways. Janus (plural jani) came to be the name of special symbolic archways throughout Rome. True to the god's nature, Britannica goes on, the first month of the year bears his name. In order to best portray the duality of beginnings and endings, though, Janus tends to be represented in a very specific way: sporting two faces. The deity could look back toward the old and forward to the new at the same time.
The Harry Potter series' wily Quirinus Quirrell boasts several parallels to Janus. On a strictly physical level, of course, he also has two faces. The professor foolishly tracked the exiled Voldemort to Albania (the novel reveals) and was subjugated by him when the dark wizard learned that he taught at Hogwarts.
Roman gods Janus and Quirinus had a lot in common with Quirrell
When the plot to steal the Sorcerer's Stone is thwarted, the sinister Slytherin abandons his weakened minion's body and leaves him to perish. Yet, the endings and beginnings parallel continues as the villainous dark wizard remains an indelible part of Harry's past and (at the time) an inevitable part of his future. Quirrell marked the beginning of the end of Harry's wonderful introduction to the magical world, and as the final "guardian" of the Mirror of Erised (in which the stone was concealed), he stood before an archway as unique as any ancient Rome's Janus represented.
According to Britannica, Quirrell has another connection to the ancient Roman pantheon. Quirinus was the name of an enigmatic god seemingly connected to Mars and Jupiter (and may have been another name for the former). This god also went by the name Janus.
J.K. Rowling herself acknowledged this link, stating on Pottermore (now Wizarding World) that Quirinus is a mysterious deity "commonly associated with war — a clue that Quirrell is not quite as meek as he appears. 'Quirrell', which is so nearly 'squirrel' — small, cute and harmless — also suggested 'quiver', a nod to the character's innate nervousness."