Just as Simon’s Quest was a direct sequel to the original Castlevania for NES, Curse of Darkness is a direct sequel to Castlevania III: Dracula’s Curse. In Dracula’s Curse, Trevor Belmont teamed up with Sypha Belnades, Grant DaNasty, and Alucard to take down Dracula. Curse of Darkness adds some backstory to this event. Apparently Dracula had two go-to guys, Hector and Isaac. These Generals in Dracula’s army are Devil Forgemasters, which means they pal around with familiars that they can manufacture, then summon and dismiss at will.
The story goes that Hector betrayed Dracula in some way in response to objections about Dracula’s actions, indirectly causing his defeat at the hands of Trevor Belmont. Ashamed at his own betrayal, Hector gives up the trade until Isaac, who remained loyal to Dracula, kills Hector’s girlfriend Rosaly. A furious Hector chases Isaac to the ruins of the castle and the story of this game begins with the playing taking the role of Hector in his quest for vengeance.