DOPPELGANGER

A recurrent motif in Gothic fiction, the doppelganger or double has
both symbolic and psychoanalytical implications. In the case of the former,
the duplication or division of a character may serve to emphasize
polemically the moral dilemmas or social disparities around which a didactic
or cautionary narrative may revolve—for example, the fate of one
who resists temptation, as opposed to one who succumbs to it; or, the
lifestyle enjoyed by a character born into privilege, set against the parallel
experience of another raised in poverty. In psychoanalysis, the motif may
emblematize the polarity of the unrestrained id against its ego and superego
counterparts. Thus, the doppelganger may become, variously, a figure
that enacts taboo desires, a seeker of arcane knowledge, or one who
pursues the drive of thanatos rather than that of eros. In both symbolic
and psychoanalytical incarnations (though these demarcations are, inevitably,
capable of definition as much by the critic as the author), the double
may be formed by duplication (where two entities effectively parallel
each other’s actions) or division (where a character is split, physically or
psychologically, into two alternating personalities). Situations such as
disguise, cross dressing, or mistaken identity may also produce contextual
implications that are analogous to doubling.

Hughes, W. (2012) Historical Dictionary of Gothic Literature