WARNING: Spoilers for The Haunting of Bly Manor.
What's the true meaning of Dani's mirror ghost in The Haunting of Bly Manor? The glasses-wearing spirit appears several times throughout the first three episodes of the Netflix series, and seems to embody all the emotional trauma that Dani (Victoria Pedretti) brings to her new job in the English countryside. As it turns out, the mirror ghost links to the much-discussed subtext of the 1961 horror movie, The Innocents, which shares the same source material—Henry James' 1898 novella The Turn of the Screw—with The Haunting of Bly Manor. The mirror ghost also informs audiences about Dani's motivations when its identity is revealed.
In The Haunting of Bly Manor—which isn't a sequel to Flanagan's first entry, The Haunting of Hill House—Dani first sees the mirror ghost at a London hostel, and doesn't seem too shaken by the experience — it's almost like she's seen it many times before. The ghost later shows up in a Bly Manor bathroom, then once again in the series premiere when Flora (Amelie Bea Smith) and brother Miles (Benjamin Evan Ainsworth) lock Dani in a closet. As it turns out, the Wingrave children are merely trying to protect their new au pair from The Lady in the Lake, but they end up inadvertently triggering dark memories from Dani's past. The mirror ghost appears mid-way through episode 2, "The Pupil", in a bathroom; it shows up again in The Haunting of Bly Manor episode 3, "The Two Faces, Part One", after an intimate moment between Dani and gardener Jamie (Amelia Eve).
The Haunting of Bly Manor reveals the mirror ghost's identity in episode 4, "The Way It Came". A flashback sequence shows young Dani conversing with her childhood friend, Edmund, and touching his glasses. A slick visual transition shows Dani touching Edmund's glasses once again, but years later at their engagement party. Later, as Dani gets fitted for her wedding dress, she feels a romantic connection with the seamstress. In the moment, Pedretti's character looks at herself in the mirror while the woman stands beside her. Dani eventually breaks up with Edmund, who dies shortly after being struck by a car. At his funeral, the ghost of Edmund wears glasses that are lit up from the headlights of the car that killed him. In England, Edmund appears in mirrors to reflect an extension of Dani's guilt and her anxiety about being attracted to women.
In The Haunting of Bly Manor, showrunner Mike Flanagan references James' 1891 book Sir Edmund Orme for the mirror ghost subplot. The original tale centers on the titular character, who commits suicide after being rejected by a woman named Mrs. Marsden, then haunts her daughter, Charlotte. Flanagan tweaks the narrative for his Netflix series by incorporating a same-sex romantic twist. Incidentally, the Edmund ghost doesn't actively haunt Dani, but rather emerges as a subconscious projection.
Edmund's mirror appearances in The Haunting of Bly Manor build upon subtextual themes that were introduced in the 1961 James adaptation, The Innocents, starring Deborah Kerr as the governess Miss Giddens. Over the years, many people have argued that Miss Giddens' repressed sexuality leads her to imagine the young characters Flora and Miles. In The Haunting of Bly Manor, Flora and Miles are indeed real characters who attempt to protect Dani from the Lady in the Lake, a tragic monster figure who gets in the way of the au pair's romantic relationship with Jamie. As a character, the Edmund ghost functions as a psychological obstacle to overcome — a liaison for love. Once Dani confronts her past, she's able to move forward with Jamie, who eventually honors her lover's legacy by telling the story of Bly Manor in the present.