Castlevania: The Story Behind It

This is how the Castlevania series starts, and what the movie will be based off. I got this from The Castlevania Realm, so thanks to to them.1

Leon Belmont was a church knight who served in an invincible two-man company with Mathias Cronqvist. Their battles were against enemies of the Catholic Church, and they in relishing this task served proudly in the name of God. Though strong of mind, their beliefs would test their friendships' boundaries and start in motion act one of the grandest of all plays. For it was the age of monsters, who were appearing in Leon's domain in their expansion beyond the Forest of Eternal Night, ruled over by the vampire Walter Bernhard. In reality, their increased presence was more indicative of evil's more-sinister desires and the activities of Mathias: When Mathias' wife passed from this world, the grief-stricken warrior blamed God, and in an act of revenge against the deity whose name in which he had fought, he secretly made a deal with Death, who would aid the vengeance-craving tactician in the collection of the three stones of alchemy for the purpose of attaining eternal life.2

Mathias orchestrated the abduction of Sara Trantoul, Leon's beloved, at the hands of Walter Bernhard in order to con his most trusted friend into destroying the powerful vampire so that he and Death could arrive at a more desired conclusion: The collection of Walter's spirit into the soon-to-be-recovered Ebony Stone, which would allow Mathias to abandon humanity in gaining eternal life, in his immortality powerful beyond comprehension. The campaign was highly successful if not for one hitch: His belief that Leon would sympathize with his plight and join him denouncing God was ill-conceived, for Leon would never take such action. Though there would be no direct encounter between the two, it was this plot and Leon's rejection of Mathias' plea that essentially created the Belmonts' eternal struggle. At some point, Mathias cast away his name and took the name of Dracula. Leon's path is meeting the challenges entailed created the means with which the family would counter the perennial threat.3

Since Leon had to leave his sword behind in storming the castle, the cognizant Rinaldo Gandolfi supplied him the Whip of Alchemy, which was strong enough to hold back evil but not strong enough to challenge Walter. He also granted Leon the ability to harness and utilize magic power in the category of enchantment, which was instrumental in his creation of the famous family arsenal. Using his new arsenal, Leon was able to rescue Sara only to discover a terrible truth: She had been bitten by Walter, and it was only by the antagonist vampire's destruction, we learned, that her state could be reversed, lest a chain of events would ultimately result in Sara joining Walter in eternal darkness. Since his defeat was impossible under present conditions, Rinaldo could speak of only one solution: Walter could be defeated, maybe, by using his own essence against him. To accomplish this, Leon would have to strike down the hopeless and eventually volunteering Sara with the Whip of Alchemy; his rage combined with her will to prevent others from suffering the same cursed fate would transform the whip into the Vampire Killer, a living symbol of her will and a weapon that could be used to destroy the undead and the divine alike. In one violent yet pained motion, Leon completed the process. In striking down his beloved, Leon created the ultimate weapon against evil, a device that while seemingly foolproof would have for its use certain consequences.4

During Walter's reign, there were others who attempted to venture into his castle and destroy him, but they failed miserably. These hunters, knights and warriors in defeat could only leave behind their weapons. During his adventure, Leon simply gathered up five random weapons (a battle axe, a vial of holy water, a dagger, a cross and a crystal) and would command them as his own; he would in using his newfound magical propensity, specifically seven specially imbued orbs, augment these new sub-weapons, reshape their attributes, and enhance their efficiency as killing machines. So by the end of his mission, Leon had at his disposal the Vampire Killer whip and five sub-weapons of now-mystical proportion. Soon after Walter's dispatching, and after revealing his true intentions, Mathias, too, relieved Leon of his presence and left behind his chief henchman, the overconfident Death, who would come to taste humble pie and more specifically the power of the newly crafted Vampire Killer. Leon had an order for the fleeting Reaper, a message he wanted delivered to the fallen angel's recently departed master: "This whip and my kinsmen will destroy you someday. The Belmont Clan will hunt the night!"5

It's true that Leon unwittingly helped create the cycle that would repeatedly threaten his kinsmen and all of Europe, so he knew that he now had a certain responsibility. To ensure the world's safety, he would have to pass down the arsenal into the capable arms of younger and more equipped family members so that they could train properly to hunt vampires and battle against all forms of evil--this a process that would have to be repeated. For if evil would always find a way to grow stronger and haunt this world, the ever-vigilant, steadfast Belmont Clan would be waiting.6

Hundreds of years later the young Sonia Belmont was a native of Warakiya (a storyline-based Romanian/Transylvanian region in Wallachia). It has been said that Sonia was trained by her uncle, who left to her possession the Vampire Killer whip. While her uncle was undoubtedly a warrior, there is no evidence of his battles, which means that he, like those before him, could have also fought against Mathias, or he could have remained idle, simply a link in the chain. It's clear that the family had been deemed a danger to the community and later banished, which might also entail a falling out with the Church. Despite public rejection, the Church eventually allied with the early Belmonts, whose ancestor Leon fought in its name, and became a guiding influence; with this degree of separation, as simply "allies," there would be no obligation for Belmont warriors to fight in any holy wars as Leon once did.7

So when monsters began to terrorize the countryside and no one really knew why, Sonia was ready to step forward with the Vampire Killer, which with Sara Trantoul's spirit came to sense evil and over time afforded Belmont heroes this same sense. She fought and defeated Dracula.8

On her seventeenth birthday, she met up with Alucard, son of Mathias Dracula, who at this point time was still in the early stages of his campaign to eradicate humans from the face of the Earth. Much earlier, Mathias had after a decades-long search met Lisa, who he believed to be the very reincarnation of his late wife Elisabetha. The relationship that followed planted the seed for the birth of Alucard, whose real name, as dictated by his father's soon-following name-change, is Adrian Farenheights Tepes. Much to Mathias' chagrin, his genes weren't as dominant as expected; as a half-breed, the procreation of a vampire and a human woman, Alucard grew at all times nurturing an inner struggle, a tortured existence he could hardly bear. His only means of control: Lisa's gentle and loving traits began to manifest within him a sense of justice counter to the teachings of his father, who thought himself to be training a future lieutenant in the war against the humans. Alucard's increasing resistance to his father's dark ways became more and more evident to the point where a split was inevitable. To Dracula, such a sudden action evoked a sense that his son was a half human, half vampire timebomb.9

There is much more background with it, but this is just some of the important stuff haha. Many of these elements will be in the film.