Kisar was one of an ancient species of assassins called Thijarians.
After Thijar was destroyed, and they were left unable to grieve or honour those who were lost, Kisar and Almak decided to leave their old ways behind and bear witness to those who died alone. The Thirteenth Doctor, Ryan and Prem accidentally came aboard their hive, where Kisar and Almak were waiting to bear witness to those who died during the Partition of India in 1947. The Doctor was not aware, until later, of their new objective to honour Prem. (TV: Demons of the Punjab)