Bumping this thread for some attention! (None of this is necessary to read, I'm merely drawing attention to a problem I share.)
I've got the same issue and I'm using Lohse as my avatar. Normally, because I'm a goody-little-two-shoes in my own mind, I take the naïve paladin route and scream to the heavens that I will not snuff the light of a life just because they're desperate and have no real sense of character. Well that's fine, I have a clear conscience and I go up to Doctor Sassypants and with all the confidence that I've yet to lose a boss fight challenge him to a 2 Lonewolf vs a horde of Buff Nurses, Distraction Demons, and HOLYGODWHATISHISARMOR himself. One may think that I immediately cried as I watched my Lizard Prince and fancy-haired princess suffer a good ol' fashion beatdown; but no, Lonewolf is amazing and there's little you can't solve with a 70 strength and a 70% crit chance, so an Apotheosis, an Onslaught(er), and an array of other various source skills later, some Distraction Demons are already dead, the nameless-lizard and Lohse both still have armor and I'm confident that I can defeat Amalamadingdong no problem. Oh. Until he possesses Lohse with no way to resist and Game Over. Sorry, you died, hope you enjoyed this edition of Dark Souls.
SON OF A B-
Okay. That was brilliant. Well played Larian, in order to defeat this aforementioned ABSURDLY POWERFUL DEMON you need to compromise your morals a bit, make some hard decisions and weaken him so Lohse can actually resist him gouging her soul to be his little bitch. Here I go, loading up an old save, I spend some time crafting, get myself a level twenty Eternal Armour, make my main-hand axe have a 200+ plus damage rating and mentally steel myself versus feeling awful about committing mass genocide on some very well-rendered NPCs. I talk to Malady, fast forward a bit and we're at the grandiose scene of candles that stretch into eternity. Let me say right now that I LOVE this game. Oh lordy it gets me good. Here I go; I click on Malady, she muses, I take the time to muse, we both support each other in doing the hard thing and even my oh-so-self-absorbed Lizard companion chimes in with a bit of "attagirl" and I finally choose the option to embrace my inner eugenicist. And nothing. That was weird, let's start the dialog again. It starts new, same choices, same musing, some pats on the back annnnnnnnd notta. Well shit. Bugs happen, sure, let's reload. Quick save go.
Same result. Some of a bitch. Let's restart the client! Sure, that has fixed most problems so far. Load in, some conversation, some mild support, annnnnnd still nothing. About sixty google searches later, some steam browsing, and I finally come here, find this thread and make an account for the sole purpose of writing this awful waste of time for anyone that chose to read it all so I can say: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFUUUU-
Anyway. Using Lohse as your Avatar means you can't fight the big baddie (presumably) without snuffing the candles, but the bug prevents you from snuffing said candles; therefore, you're left in an infinite cycle of smashing your (my) head into a keyboard and dallying around doing other quests somewhat like what I do when I find things to distract myself instead of doing the dishes. And like my dishes, eventually my wife will start throwing things at me and I will inevitably be drawn to the kitchen only in Divinity I can't fill bowls with water before-hand to make the scrubbing easier and (hopefully) some-sort-of bacteria demon won't rear from the garbage disposal and suck my soul out and command me to do this shit daily. If someone does know a fix pleeeeeease send it my way, I'm rather obsessed with this game and would like to complete it soon. Otherwise, oh Larian, I await your bug-fix with great apprehension.