Suddenly a Boethiah Cultist attacks while shouting about killing J’Zhirr. He is a strong Dunmer so J’Zhirr quickly climbs upwards to escape from his blows. Being not as agile, the cultist takes a while to figure out how to reach this one. Meanwhile, J’Zhirr takes the opportunity to shoot at him.
This is the first time J’Zhirr encounters a Boethiah Cultist. Before this, he does not know that they are even a thing. Going by the name, one can safely assume that they are the worshippers of the Daedric Prince who rules over deceit, conspiracy, secret plots of murder, assassination, treason, and unlawful overthrow of authority. As Dark Elven cultural advances are attributed to Boethiah, it is no surprise to find Dunmers among his worshippers.