Helping Erandur battle through Nightcaller Temple in search of the Skull of Corruption, the Dragonborn is blocked by Veren Duleri and Thorek, who label Erandur, a former priest of Vaermina, a "traitor." He immediately becomes hostile and attacks the two on sight.
Thorek: "The orcs have breached the inner sanctum, Brother Veren."
Veren Duleri: "We must hold. We can't allow the Skull to fall into their hands."
Thorek: "But... no more than a handful of us remain, brother."
Veren Duleri: "Then we have no choice. The Miasma must be released."
Thorek: "The Miasma? But, brother..."
Veren Duleri: "We have no alternative. It's the will of Vaermina."
[After speaking to "Casimir"]
Veren Duleri: "Brother Thorek, we must remain here and guard this Skull with our lives if necessary."
Thorek: "Agreed. To the death."
Veren Duleri: "Then let it be done. Farewell, my brothers!"