There are three types of legitimate vampire slayers in this world.

Type 1 – Transformarians, this is the largest group of vampire slayers.  They are the ones that are "self made" you may say.  Usually they have seen first hand a vampire attack, and sometimes they themselves have survived an attack.  Based on this experience they join a small segment of human society which accepts that there are things beyond our rational comprehension, bumps and shadows in the night which can not be explained by science or even religion.  In this moment of clarity they have made the choice to become a vampire hunter. 

Now, in order to become a board approved, licensed transforma, one has to undergo an ancient ritual in which they consume the fresh raw meat of a sheep that has been killed by a wolf.  This ritual gives them limited psychic vision, strength and enables them not to fear the dark things they fight. Any idiot that is stupid enough to forego the ritual and start wondering the streets at night with a cross and a wooden stake is likely to be dead by sunrise. . .if the vampires care enough to take them seriously.  Even when one undergoes the ritual and appropriate training to become a true transforma, they are the group most likely to be killed in the line of duty.  The ones that usually tend to survive are either exceedingly street smart or have formed alliances with certain vampire clans for the sake of protection. 

Type 2 – Sabbatarians, this is the second largest group of slayers.  These are females that are born on a Saturday.  These slayers are born with innate abilities that make them natural slayers, these females are quicker, stronger and smarter then your average or even above average human.  From a young age, sabbatarians have dreams of vampires and psychic visions which they may or may not choose to ignore.  While transformarians learn to make educated guesses with regards to whether or not they are in the presence of a vampire (e.g. paleness, dated clothes, a pressing need to bite you) sabbatarians, on the other hand, especially with time and growth, develop sharp, intuitive abilities which can tip them off that there is a vampire in the immediate vicinity.  This ability alone ensures a longer life expectancy.

Even though females born on a Saturday have natural gifts, in order to make full on slayer status one has to be called to duty.  The slayer guardians observe sabbatarians from the day of birth.  Only the best of the best are selected and recruited to join the ranks, with the option to turn it down.  Usually this call to duty occurs around the age of 15, however exceptionally in tune sabbatarians may be called sooner and, in times of high demand, some may be called later.  Whenever a vampire stumbles upon a young sabbatar, they will seek to kill them before they are given the call. 

And then there is Type 3 – Dhampirians, the smallest, most elite badass slayers on earth, who also carry the heaviest burdens.  Dhampirians are created when a human female survives a vampire attack while pregnant.  Now normally when this happens, one of two things will occur, either the rapid blood loss will shock the body and cause the mother to miscarry, or the superhuman strength and needs of the baby will drain the mother causing the eventual death of both the mother and child. However in the rare event that she is able to carry the baby to full term and deliver the child, the baby will be born a supernatural human with vampire genes.  This combination creates a human with speed, strength, and abilities on par with vampires. 

From birth, Dhampirians are aware of who they are and the mark they carry.  Though they may choose to ignore or walk away from their destiny, it is always deeply ingrained in them.  Like sabbatarians, they also may find themselves being hunted at a young age by vampires seeking to end their lives before their gifts are fully able to come to fruition.  For this reason, they are often taken from their families at a young age and put into the custody of the hunter guardians, isolated from the rest of society.  Once they fully come into their gifts they make the fiercest and most desired hunters, sometimes leading to jealousy and conflicts with other types of slayers. 

Evangeline was born a dhampir. 

But even amongst the elite ranks of the dhampirians Evangeline was the cream of the crop.  From an early age she was the best and she knew it.  She was the fastest, the most agile, best knife thrower, top stake wielder, she was voted by a landslide "slayer most likely to succeed" for her class.  A lot of dhampirs carry around self hatred at who they are.  Unlike other types of slayers they didn't make the choice to be or develop who they are, they were called to their destiny from the moment of birth.  But Evangeline never once wanted to be anything other than a dhampir.  The thrill of the hunt, the power of the "kill," the fear she garnered from slayers and vampires alike, she loved it, she lived for it.  Her guardian, Sensei Williamson warned her that her arrogance would be her downfall but she laughed at him.  What the hell did he know?  Guardians were bottom feeders, most were little more then glorified transformarians really.  Just because they read a lot of books, had a wide knowledge of vampire history and were versed in combat techniques, didn’t mean they knew what the hell was going down on the front lines.  She didn't give a damn what any of them thought and flaunted that fact blatantly.  She didn't worry about downfalls, downfalls were for the weak and fearful and she was neither.