In Western Judeo-Christian tradition evil has a personal identity which creates black and white duality and rivalry between two forces. In case of Hinduism good and evil are mind-made concepts. Suffering is a product of ignorance gathered in previous lives and distributed in the present one according to prarabdha karma. During Krsna’s nara-lila demons coming to Vraja must be very fortunate and advanced souls to have access to such private play, they are liberated personally by bhagavan swayam, which makes me think that they are not really demons, but close friends pretending to be "bad guys". What do you think?