Vampire Hunter D

While walking her guard rounds in the country, 17-year-old Doris Lang, the daughter of a deceased werewolf hunter, is attacked by Count Magnus Lee, a 10,000-year-old, long-lost vampire lord (also known as a Noble), who intends to make her his new vampire bride.
Doris later encounters a mysterious dhampir and vampire hunter, known only as D, and hires him to protect her from Count Lee. While in town with Dan, her younger brother, and D, Doris is confronted by Greco Roman, the mayorâs son, about the Countâs attack and D, and promises to help her if he has Doris for himself. When Doris refuses, Greco reveals what happened to the entire town, including Dan. D requests that the authorities, including Grecoâs father, the town sheriff and Dr. Feringo (Fehring in the English dub), should hold off Dorisâ incarceration at the local asylum until he kills Count Lee.
That night, D is attacked by Rei Ginsei, Count Leeâs servant and a mutant with the ability to warp the space around his body, and Lamika, Count Leeâs daughter, who is highly prejudiced against humans and dhampirs. D holds off the attack and orders the pair to return to the Countâs castle. The next day, he travels the castle and attempts to confront the Count. Aided by the symbiote in his Left Hand, D holds his own against the Countâs monstrous minions, including Rei and his companions Gimlet, Golem and Chullah. While in the castleâs catacombs, he is ensnared and captured by the Snake Women of Midwich. Doris is then kidnapped by Rei and brought to the Count. Using his vampiric powers, D kills the Snake Women, rescues Doris before she can be killed by Lamika, and escapes the castle.
In town, Greco overhears a meeting between Rei and a messenger from Count Lee, who gives the former a candle with Time-Bewitching Incense, a substance powerful enough to weaken vampires and dhampirs. Dan is taken hostage by Rei, and D comes to his rescue, cutting off Reiâs hand in the process and discovering that the candle is a fake. Meanwhile, Dr. Feringo, himself a vampire in league with Count Lee, leads Doris into a trap but is killed by Lamika when he begins requesting to share Doris with the Count. Greco then appears, using the real Time-Bewitching Incense to severely weaken Lamika, but is overpowered by Dan and D. Afterwards, Doris, who has by now fallen for D, tries to convince him to live with her and embraces him. This starts to trigger D's vampire side, but, unwilling to bite her, he forces her away from him.
The next morning, Greco is confronted and killed by Rei, who uses the real candle to weaken D, allowing him to kill the vampire hunter with a wooden stake. Doris and Dan are then captured and taken back to the castle. Lamika tries to persuade her father not to allow a human into the family, but Lee reveals that there is no harm in doing so, as Lamikaâs own mother was a human - making her a dhampir instead of a full-blooded vampire. Rei also requests that the Count give him eternal life as a member of the Nobility, but he is coldly rebuffed.
As a mutant attempts to devour Dâs body, his Left Hand revives him just in time for him to kill the monster. As the processional for the Count and Dorisâ wedding takes place, Dan, having escaped his cell, attempts to attack Lee, but falls into a chasm before being saved by Rei. In retaliation for not fulfilling his request, Rei attempts to weaken the Count with the Time-Bewitching Incense. However, Lee, who is too powerful to be weakened by the Incense, kills him. Before Doris can be bitten by the Count, D appears and engages in a climactic battle with Lee, and succeeds in stabbing the Noble with his sword. A weakened Lee attempts to influence Doris into killing D, but she is broken out of the trance by Dan, who arrives with Lamika. D then uses his powers to enact the destruction of the castle, and it is implied, because of these powers and their resemblance to one another, that he is the son of Count Dracula, the legendary Ancestral God of Vampires. He then tries to persuade Lamika into living as a human, but she chooses to die as a member of the Nobility with her father.
D, Doris and Dan escape the collapsing castle. The dhampir then sets off under a now clear blue sky. The Langs bid D goodbye as he looks back briefly to them and smiles.

Question: How is Dan related to Doris?
Answer: brother