“No, this is not the beginning of a new chapter in my life; this is the beginning of a new book! That first book is already closed, ended, and tossed into the seas; this new book is newly opened, has just begun! Look, it is the first page! And it is a beautiful one!”
― C. JoyBell C.

“Why do you follow him? What can he offer you?

Knowledge, child. There is no keener mind in the galaxy than that sour chunk of meat that occupies his skull. He has forgotten more about the inner workings of man and xenos alike than any Apothecary has ever known. I came to him to learn how to craft new and better contagions, so that Grandfather's blessings might be shared more freely. There are secret plagues from Old Night in these containers and virulent infections culled from crumbling bones of long dead aeldari. And with these raw materials and his aid, I have made wonders and horrors undreamt of by even the most glopsome of my brothers. Plagues that would devour even the rubbery flesh of Grandfather's children...

Daemons are not susceptible to mortal plagues.

No, they are not. And yet I have seen the results myself. That is what he offers me, child. In his shadow, I grow pleasingly feculent.

And what does he get out of it?

Were you not listening? Plagues, child. Swift plagues that can ravage entire systems at impossible rates. Oh, his mind is a thing of broken beauty. Even Abaddon cannot conceive of genocide on such a scale - it is not war to our Chief Apothecary, but simply...pest control. Imagine it. A great silence, falling all at once across a system. A sector. Every imperfect thing, snuffed out like a candle flame. And then... Ah, and then, a new beginning.”
― Josh Reynolds, Fabius Bile: The Omnibus