"his face assumed something of the appearance of theirs"

Gil-Martin’s ability to assume the appearance of anyone he contemplates recalls the shape-shifting powers of the devil. Though Christianity characterises his ultimate form as thoroughly monstrous, Satan is able to assume alternative appearances at will in order to trick people into falling into his power. Frequently he adopts the guise of a debonair young gentleman, as does Gil-Martin.
A suaver Satan from an 1870 edition of Punchinello magazine
Public DomainA suaver Satan from an 1870 edition of Punchinello magazine - Credit: Punchinello