"Did this 'prophecy' give you a reason to rattle off on some well-deserved vay-cay? I mean, I get it. If you wanted a few escorts to spice things up, you should have just told me."
Asdrubael Vect is the leader of the Dark Eldar Kabal of the Black Heart, and through various schemes and political maneuvers, is the ruler of the city of Commoragh.
Vect is one of the oldest living Eldar, and one of the few that have lived since before the Fall of the Eldar. Vect has been able to maintain his power through manipulation and scheming, oftentimes using convoluted plans to have his rivals killed off. For example, he once gifted a rival Archon a box that secretly contained a black hole, killing him as soon as he opened the box. Another time, he killed the other survivors of the Fall by allowing three space marine chapters to invade the city after he stole a Salamanders cruiser and had the other Archons fight over it. One time he kidnapped a human simply to have tea and to retell the story of the Fall, allowing the human to live (but not without telling him he put laxatives in the tea before the human's next torture session).
The only time his power has been threatened was in the Gathering Storm, when a Daemon invasion of the city caused massive political chaos and had even his allies question his fitness to rule. Many of them left to join the Ynnari after his many failed attempts to assassinate Yvraine. He ended up dying, but came back and killed every non-loyal archon who came to his funeral making his rule almost completely unchallenged.
Vect was contacted by Eldrad Ulthran while in the middle of a party, which Vect used as an excuse to leave the party while the other attendees slowly died of gas poisoning (per Vect’s plans). Eldrad tried to warn Vect that the End Times were coming, and asked Vect to do him a favor by distracting the Imperium with a raid while he performed a ritual that would summon Ynnead into existence. Vect refused to take Eldrad’s warnings seriously, saying that he wasn’t going to waste his time when the Eldar have always been in peril and that he wasn’t going to listen to any more superstitious nonsense. After the call ended, a servant came to tell him that the Gate of Khaine had broken open. Anticipating this, he sent a large army to intercept the Inquisition and force them to negotiate.
After he had brought Fyodor Karamazov to his floating ziggurat, Vect revealed that he knew Fyodor had infused with the Star-Child, a fragment of the Emperor's psyche. Vect, and his Master Homunculi Uriel Rakarth, explains that they would torture Karamazov, as the Star-Child's untainted soul would provide enough power to completely ward off Slaanesh from devouring their souls. Karamazov however responded with amazement to their plan, and called Vect a benevolent leader for his effort to potentially save the entire Eldar race. Much to Vect's bewilderment and Rakarth's annoyance. Fyodor's energy of friendship causes Vect's heart to literally warm up, slowly melting him. Despite their various attempts on torturing Karamazov, they all ended in futility thus causing his "un-suffering" energy to spread throughout Commoragh, slowly killing its inhabitants with positive energy, much to the lamentations of Vect.
As a last ditch effort, Vect tells Fyodor that he sent not only Kaldor Draigo to the Arena, but also all of his human forces. Fyodor was surprised and hurt by this information, and this pain caused Vect and Commoragh to be fully revitalized and empowered even further. Vect gloats to Fyodor and proceeds to bring Fyodor to the Arena to witness the Inquisition's gladiatorial fight.