Vampire ( vam-pire )

; the reanimated body of a dead person believed to come from the grave at night and the blood of persons alseep.

; one who lives by preying on others.

Song Seoyeon was the sole survivor of her family, who were either killed or captured in a huge massacre by the Demonic Ellimination Association (DEA) years ago, whose main intention to get rid of vampires, human-vampire hybrids and other hybrids who serve as threats to mankind. She was later found by Kim Suho, whose parents were killed too. He brought her back to the mansion he onced live in with his parents, and that's where she met the others who shares the same fate. 

Suho later then created a group called EXO, and was known as one of the most (in)famous gangs in Seoul. 

Unlike vampires, human-vampire hybrids does not have red eyes all the time. But occasionally, they would develop red eyes as a sign of hunger, which can be easily detected as a threat to humans. They can stay up to 3 to 4 months without feeding. They could grow old like humans too. Their body build too is very alike to normal human beings.