Who is Apuleius, and what part does he play in this story?

Apuleius is the author of The Golden Ass, the Latin language novel that was the basis for C.S. Lewis’s retelling of the myth of Cupid and Psyche in his novel Till We Have Faces. It is debated whether Apuleius’s narrator, Lucius, was a persona representing Apuleius himself, but many critics agree that it is a strong possibility. However, Lucius was retelling the story of Cupid and Psyche in his narration, since it was actually told by a different character. This makes it difficult to see his direct influence on the telling of this story. Lewis believed there were some inconsistencies and a general vagueness in this version, so he sought to correct that in his. In order to achieve this, he chose a strong female persona named Orual to narrate his version of the tale.
We can gather from these changes that the part Apuleius plays in Lewis’s version is virtually nonexistent, except for his philosophical and poetic influences. It was Lewis’s decision to focus so strongly on the narrator’s point of view, with interesting personality traits and emotional turmoil, along with what may have been perceived at the time as an ability to appeal to both male and female readers. In this way, the spirit of the narrator Lucius is maintained, since both he and Orual are very adept at drawing the reader into the story. Although Lucius is considered to be a bit manipulative in terms of playing "mind games" with the reader, Orual manipulates through emotion and plotting.

C.S. Lewis' novel 'Till We Have Faces' is a retelling of the tale of Cupid and Psyche within a story called 'The Golden Ass' by Apuleius. However, the character Apuleius does not make an appearance in 'Till We Have Faces'.
Though many of the same themes (such as rebirth, transformation, and an obsession with the supernatural/magical) are present in both stories, 'Till We Have Faces' is much more a story concerning the notion of individuality and being true to oneself, as well as accepting self-responsibility and not blaming outside forces for our decisions; though there is forgiveness in the blame, for Orual is blinded by naivety, ignorance, and her own personal emotions towards Psyche.
Where 'The Golden Ass' ends with Lucius receiving salvation via the intervention of a god, 'Till We Have Faces' ends with Orual facing a god and the self-realization of her own influential hand in the tragedies of her life and a clearing of the delusion that has obscured her face from the truth.