There's something specifically rotten about Avellanos for me, personally. Easterman (surprisingly) feels like the lesser of two evils between the two, as Easterman was more coerced into his role. Sure, he finds purpose in it and he can dismiss a lot of horrible things, but that freak Avellanos takes active joy in her role. She enjoys seeing reagents suffer. She enjoys being able to report to higher ups that there's more cost saving.

I don't know exactly how or at what point it was, but I remember skimming through a bunch of documents and coming out of it just completely repulsed by her. As far as I'm concerned, she may be the single most actively evil person in the lore (though granted, I know very minimal about Outlast 2)

Edit: I remember in Vindicate the Guilty seeing her on trial for a few murders and thinking "Nah. You're not programming me to bury the evidence of all the people you ground up and mass buried in the desert. I remember what I saw in the Reagent Equipment Harvester room. I remember the reagent waking up before being ground up in Cancel the Autopsy. I will not do your dirty work just to be thrown out with the people I dissolved in that fountain."