Mod overview: Unfaltered Virtue - Omni-guides/Tuxborn GitHub Wiki
Unfaltered Virtue is an overhaul of the quest to destroy the Dark Brotherhood.
The current version of this mod had all lines generated by AI yanked by the mod author. We therefore recommend that you turn on subtitles while playing Unfaltered Virtue, at least for the duration of the mod, if you weren't already playing with subtitles active.
This mod's questline requires interacting with Sybille Stentor. Sybille is not Essential. And given that we're running the Unmasking Sybille mod in our load order, it's worth noting that "killing Sybille" is one of the outcomes of that mod. If you choose to kill Sybille as part of that mod, and you run it before you run Unfaltered Virtue, it will cause quest breakage in Unfaltered Virtue in a scene where Sybille's presence is required.
The following workaround was posted on Nexus as a means to get around this problem via the console:
Open the console before you enter the Penitus Oculatus building with Babette and enter:
prid 198C5
setav aggression 0
resurrect
The scene should play out correctly when you enter the building, and then you can kill her again after.