Direni

Direni is a man who lives in Devil's Crossing. Before the Grim Dawn, Direni was a prisoner there.

Campaign
After you find Cultist Orders, the side-quest A Cultist in the Midst begins.

You can go back to Devil's Crossing to confront Direni. Once you do, you'll be able to choose whether or not to kill him.

If you let him live, he'll give you a Strange Key, which can also be dropped from the cultists located in the Cultist's Lair or outside the Depraved Sanctuary. You'll also encounter him again in Act 2 inside Cronley's Hideout as an enemy.

If you kill him, you'll receive 500 Reputation with Devil's Crossing and a vial of Blood of Ch'thon.

Quotes

 * "Brothers of the Blood, The Aetherial presence in Burrwitch grows stronger with each passing day. We are shifting our operations beyond the city limits where we may proceed with our plans undisturbed. Our focus now turns upon Devil's Crossing, where our newest agent, Direni, has successfully sabotaged their water pump. Soon that irksome group will be forced to flee their sanctuary, and then they shall be at our mercy. Ready yourselves, brothers. Soon we shall drink of their blood! - Salazar, Blood of Ch'thon" - Cultist Orders