Roma Mater falls into a literary subgenre some critics call adult fantasy. The term adult fantasy probably came into being because many, probably most, readers tend to think of fantasy as a kind of children's literature; the word adult serves to distinguish books like Roma Mater from what such readers expect fantasy to be. Works such as J. R. R. Tolkien's Lord of the Rings (19541955) and Richard Adams's Watership Down (1972) are examples of adult fantasy. They have themes commonly associated with adult literature: complex sexual relationships, the challenges of raising families, the difficult choices between survival and sacrificing oneself for others, and similar issues associated with the problems of adulthood.

It is possible for young readers to miss the complexities of such novels—even to be confused by the violence, sex, and truths that seem to be elusive and obscure. Even so, the Lord of...