The characters of Lying: A Metaphorical Memoir include the following:

• The author, Lauren Slater, who describes mental illness as she may or may not have actually experienced it, taking readers inside her experience where what is real and what is imagined is hard to distinguish.

• Another character is the author's dissatisfied mother, whose difficulty accepting her mundane circumstances may have influenced Slater's actual or pretended episodes of mental illness in childhood (whether epilepsy or feigned epilepsy).

• Dr. Hayward Krieger is an ostensible professor at the University of Southern California, who allegedly confirms readers will not know if Slater really suffers from epilepsy from reading Lying. Professor Krieger is exposed as a hoax by a New York Times Book Review writer.

• Dr. Neu, a neurologist who supposedly writes articles about Slater's condition and performs a harrowing brain surgery on her to separate Slater's left and right brain lobes. A college counselor tells Slater that there is no Dr. Neu, but Slater continues to believe she is the special subject and beneficiary of his genius.

• Although not characters in the traditional sense, the mental disorders of epilepsy and Munchausen’s syndrome are also key characters in Lying. Epilepsy is a neurological disorder where brain activity becomes abnormal, causing seizures, unusual perceptions or behavior, or loss of awareness. Munchausen’s syndrome is a mental illness where the person acts as if they have a physical illness (like epilepsy in this case).