After Rhoshamandes kills Maharet and Khayman, Lestat severs his left arm and, not wanting to take a life for a life, brands him with the mark of Cain—a symbolic order from Prince Lestat to all vampires to neither harm nor kill Rhoshamandes, lest they be harmed or killed themselves. Although the mark spares his life, it is a bane, for wherever Rhoshamandes goes, vampires curse him and spit on him, so that Rhoshamandes will never be accepted into vampire society again.
The concept of the mark of Cain comes from Genesis 4:8–16, where Cain kills his brother Abel, and God makes him a wanderer in the world but places his mark on him, so that no one can kill Cain lest they suffer a sevenfold vengeance.
The mark of Cain appears in Prince Lestat (2014) and Prince Lestat and the Realms of Atlantis (2016). For more perspectives on the mark of Cain in the Vampire Chronicles, read the Alphabettery entries Khayman, Lestat de Lioncourt, Maharet, Mekare, and Rhoshamandes.