Ascertes Hallow was a human, king of Hallowvale, along with his wife, the icyene Queen Efaritay, and the father of Safalaan. Hallowvale was an ancient civilisation located in what is now the swamplands of Morytania, during the Second Age.
During his time, Hallowvale was said to have flourished, its many peaceful settlements existing as far north as the Northern Sea. However, during the God Wars, the vampyre Lord Drakan attacked Hallowvale, managing to take Ascertes captive. This forced Queen Efaritay to surrender unconditionally.
During The Lord of Vampyrium, Lowerniel Drakan claims he did not kill Ascertes, and that one of Safalaan's allies killed his father. Vanescula Drakan denies that it was her, meaning one of the Myreque (including the player) must have killed him if Vanescula is telling the truth. It was later confirmed that Vanstrom Klause was Ascertes, having been killed by the player during Branches of Darkmeyer.
In the Icyene graveyard, it is found out that Dessocles and Apherna are his parents.