Penitus Oculatusby wSkeever is an excellent mod that allows you to join the Penitus Oculatus after you destroy the Dark Brotherhood. It allows you to access most of the items from the Dark Brotherhood questline, and allows you to hunt down both Dark Brotherhood remnants and Thalmor infiltrators for the Empire. 

Among those remnants are Cicero and Babette, who escape justice in vanilla and potentially serve as an explanation for a Dark Brotherhood resurgence in future games even if you destroy them in Skyrim. This mod is for those who, like myself, want to keep that plot hook open while still experiencing a more robust alternative to the Dark Brotherhood. Or it can serve for those who feel uncomfortable killing a child in the game no matter the reason. All it does it change the mod's Babette NPC from a custom child to an adult Breton vampire. Once you kill this "Babette," you'll find a note on her corpse from "The Child" hinting at the real Babette's survival but leaving no trail for your character to follow.

I've always thought that Babette is one of the most unique characters Bethesda cooked up for Skyrim, and while we all know why she isn't present in the sanctuary when you kill them all in vanilla, I always liked the implication that her survival instinct is just that more refined than her brothers and sisters. The scenario I suggest in this mod, that she recruits a powerful but witless vampire who owes her a debt to die in her stead, appeals to me as a decision her character would make. It also has the added bonus of side-stepping any child mod conflicts you might have! (The Babette in the original mod is custom child NPC race, and thus won't have the edits to Babette any child mod makes.)

COMPATIBILITY AND INSTALLATION:
Should be compatible with everything, it edits one base NPC in one mod and adds a single written note, if there are any conflicts I will eat my hat. Should be plug-n-play ready even in a current save, the only possible issue I can imagine would be the original mod's Babette already having been spawned into the world, which doesn't happen until you get the quest to kill her. Even then, this mod edits the NPC's base, so feasibly it should work no matter when you add it. Useless if you've already killed her, obviously.

ANTICIPATED QUESTIONS:
Why not save Cicero too?
I feel it goes against the spirit of wSkeever's mod if you don't successfully kill at least one of them! Besides, you can meet Cicero before you even hear about the Brotherhood in-game. He's a chekov's gun that goes unfired when you destroy them in vanilla. Here, your character's relationship with Cicero gets closure, however brief and violent, and the real Babette can live on to restore the Brotherhood if a future game demands it.

What's the deal with Fake Babette?
I see her as a vampire of a smaller Skyrim clan that ran afoul of Babette at some point in her 300 year lifespan and is now an asset Babette can call upon. I see Babette, along with Movarth and Sybille Stentor, as one of the elder vampires of Skyrim not associated with the Volkihar, an apex predator in an underworld full of predators. As such, when Babette makes a demand, lesser vampires listen up. Babette rightly clocks the Dragonborn as an existential threat and throws an expendable patsy to the wolves to mask her escape, possibly in collusion with the original mod's new Listener as a safeguard to ensure the Brotherhood's survival.

What if I want to kill the real Babette?
Then you're looking for the original mod, what are you doing here?

This description is way too long for a mod a five-year old could have made.
Of all the people in this world who like the sound of their own voice, I am far from the worst you will meet in this life.


All credit to wSkeever for Penitus Oculatus, they did the real work here, I'm just an interloper.