Another of Beyond the Black Rainbow‘s main themes is identity. Over the course of the movie Dr. Nyle experiences a radical change of personality whose roots lie in the terrifying drug experience he had in 1966, under Mercurio Arboria's supervision. Being exposed to his shadow side so intensely crippled not only his mind, but his body: Barry is forced to use appliances such as a wig and contact lenses. Similar to many Lovecraftian protagonists, Barry Nyle is ultimately a pathetic character: his far-reaching knowledge, restrained demeanor and carefully controlled work environment are unable to dominate the forces of irrationality and chaos burning in his mind. In the end, the doctor undergoes a physical and psychological transformation where he forfeits all control and gives in to madness.
