Vengeance as a concept is considered heretical by the Hive. By their logic, those who die deserve death and extinction, because they can not continue proving their right to exist. Savathun has pointed this out to Xivu Arath, calling both her and Oryx hypocrites for wanting to wreak vengeance upon us for killing their family members. Eris is antithetical to the Hive, because she pursued vengeance against the Hive while using their magic to do so. This was most evident in Season of the Witch, where she became a genuine Hive God of Vengeance and gained enough power to banish Xivu Arath from her Throne World. She even survived being killed by Keit'ehr and appeared in her own Throne World. The Echo of Navigation dismisses vengeance as "sentimental", and he said this about the Oryx we killed, though he's missing important context. Namely, not only was Crota Oryx's son, but also a pillar of his tithes. Without him, Oryx was failing to keep his worm properly fed. But there is a distinct irony to this dismissal of vengeance by the Hive's interpretation of Sword Logic, and it exposes the hypocrisy foundational to the three Hive Gods - vengeance is what drove the Krill siblings to become the Hive in the first place. They wanted revenge upon Taox for allying with the Helium-Drinkers and killing their father, the Osmium King. Xi Ro most directly swears vengeance upon Taox in their shared oath. They sought out the power to allow them to take vengeance, and that is how the Worm familiar, and the Witness, guided them to the Worm Gods to take up their larvae and become the Hive. Therein lies the irony. By being the God of Vengeance, Eris Morn embodied the core nature that drove the Krill siblings to embrace the Worm Gods, the Sword Logic, and Darkness as a whole. Vengeance for their father and the Krill of the Osmium Court. Oryx even tells Crota that killing Taox is his oath, not one his son bears. It makes me wonder what will be in store for us whenever Taox finally emerges in the story. Plenty of people have theorized she is tied to the OXTA machine, given how much info relating to the Hive was found within it and made its way into Cabal culture. If Xivu Arath survives Heresy, I know for certain she'd be on a literal warpath to finally fulfill that vow of vengeance.