Hold up-- isn't Orin the sister of the DU? It was confirmed as far as I remember.

Did something change or did you guys fanon it differently?

Okay, we’ve got quite a few such questions. Let’s figure it out a little bit

!Spoilers about Dark Urge and Orin’s origin!

Orin is a blood-kin “sister” with the Bhaal’s blood in her veins, but she can hardly be called a real sister, because the blood of Bhaal, the blood of Dead God, is the only thing that can really connect Dark Urge and Orin. However, her father is Sarevok Anchev (and her mother is Helena Anchev, who’s also Sarevok’s daughter.. Bhaal’s family is funny yeah yeah *sarcasm*), while Dark Urge doesn’t have parents and was just created by Bhaal. So, Orin is not a true sister or something like that. And we follow this canon with Marrow’s story. They don’t see sisters in each other, but the legacy of one god

And even if she were a sister… It doesn’t seem that anyone in Bhaal cult thinks about morals at all. In theory