Although little noticed by the science-fiction community when it was published, The Mirror drew a substantial readership and brought some new elements to the time-travel novel. It departs from a focus on the mechanics of time travel and uses time travel to set up the stories of the two main characters.
The novel neatly disposes of the “changing the future” possibility, in a way now common to time-travel tales that do not lead to alternate futures or worlds. When Shay becomes Brandy, her knowledge of the future is fragmentary. Larger events, such as the two world wars and the changing demand for minerals from the Boulder region, are beyond her influence. Those in her own life that she remembers from family lore occur regardless of any attempts to avoid them. The Mirror handles the paradox of two Shays living in the same time period by the grandmother’s stroke.
In addition to its time-travel potential, the antique mirror has darker powers. At least five sudden deaths occur in close proximity to the mirror at its times of activation. Corbin and Lon both die this way, as does Brandy’s father. Only Brandy recognizes the connection. The men truly loved by the women of Brandy’s line escape this fate. This seems a coincidence rather than a thematic subtext, however, until the mirror leaves the family’s hands for good just as Brandy (in Shay’s body) begins to love Marek.
The book’s greatest influence probably has been on genres other than science fiction. An innovative cross-genre novel, it is a precursor of other genre-mixing novels that blend elements of the historical novel or romance with time travel and/or horror elements. Later examples of such mixes are the enormously successful A Knight in Shining Armor (1989), by Jude Deveraux, and Diana Gabaldon’s Outlander (1991) and its sequels. An entire subgenre of time-travel romances followed in their wake. Silhouette’s Shadows line, which features modern gothic novels, many with horror elements similar to the eerie mirror and Gingerbread House in Marlys Millhiser’s novel, also became quite popular. Millhiser published several horror and romantic suspense novels before The Mirror appeared. Her subsequent work includes a mystery series set in Los Angeles, California.