Part of what makes Netflix's Castlevania adaptation shine so brightly is its terrific ability to exceed any and all expectations placed on it. Video game adaptations have an infamous history of not working in film, but Castlevania manages to thrive in a streaming television format by taking the time and effort to flesh out its characters and world. The show's first two seasons told the story of Trevor Belmont, Adrian Tepes and Sypha Belnades' bloody crusade to kill Dracula, ending with a successful assault on the iconic vampire's castle and the fulfillment of their mission.
Castlevania Season 2 also introduces two of Dracula's human servants, Isaac and Hector. Referred to as "Forgemasters," the humans are able to fill corpses with the spirits of the damned, pulled straight from Hell to create terrifying demonic hordes. Hector is a simple farm boy, while Isaac is a Muslim slave who was abused by his former master. This is the origin of Isaac's distaste for humanity and is why he serves Dracula, despite the vampire general's plans to drive humanity to extinction. Dracula rewards Isaac's devotion by saving him from fighting against his would-be murderers, sending him through a magic mirror to the deserts of Northern Africa.
It's Isaac's journey back to Europe that changes him, as he amasses a demonic army of his own. Season 4 opens on him rebuilding a devastated town, ordering his monstrous forces to carry out simple masonry while he discusses philosophy with a particular bug-eyed demon. The demon is curious as to why Isaac cares about rebuilding the town and is particularly articulate due to its past life as a Greek philosopher. It also feels an inherent wrongness to the situation, as night monsters like it are supposed to "kill, destroy and despoil." In answer, Isaac says they are but tools of their Forgemaster, and that he will use them to any purpose he sees fit.
This is an oblique metaphor for the idea of telos, a term used to refer to a person or thing's inherent purpose. It was fittingly coined by Aristotle, who was himself a Greek philosopher. If the night creatures are tools meant to destroy, then Isaac is using them to an inefficient end. It would be like using a screwdriver to hammer nails down. But Isaac further decries this metaphor, recanting his earlier statement and denying that the night creatures are tools at all. He offers the bug-eyed demon a blackberry and smiles as it recalls memories of its past life. They are people and individuals in their own right, even if their outside shells are hideous.
The bug-eyed demon further insists that its purpose is to fight and to be commanded by a Forgemaster. Isaac responds by offering up a particular quote, one he also references earlier in the series: "One day Hell will be emptied, and its doors will rattle in the wind." This isn't an original invention of the show's writers and is, in fact, a reference to an Islamic hadith from the Kanz al-Ummal. While most Muslims rely primarily on the Qur'an as a source of spiritual guidance, supplementary wisdom is often found in hadiths, recorded stories of the Prophet Muhammad's words and actions.
This hadith in particular refers to the question of if punishment in Hell is to be eternal. Isaac believes that according to the wisdom of the Prophet, Allah's messenger on Earth, Hell is meant to be temporary. He even quickens that process, as every night creature he raises is another sinner now absent from Hell. He states to the bug-eyed demon that if their punishment in Hell is temporary, their service on earth must be temporary as well. This is why he doesn't believe them to have a specific ascribed purpose or even be wholly subservient to his whims. Castlevania achieves a dual purpose by drawing on Islamic philosophy, fleshing out Isaac's motivation while also subtly underlining the ways his background influences his current worldview.
Castlevania stars Richard Armitage as Trevor Belmont, Alejandra Reynoso as Sypha Belnades, James Callis as Alucard, Theo James as Hector, Adetokumboh M'Cormack as Isaac, Jaime Murray as Carmilla, Jessica Brown Findlay as Lenore, Bill Nighy as St. Germain, Malcolm McDowell as Varney and Marsha Thomason as Greta. All four seasons are available to stream on Netflix.