My Player (one on one) had a (strong) friendship backstory with Nulia, he was next to a few others the only friends of Nulia. My PC has no idea yet (he thinks she died in the churchs fire) of what Nulia plans on lamashtu and the destruction of Sandpoint. When the chapters final boss battle comes in, should I let my player (after a great battle) talk things up with Nulia? Even make her regret and become a party member/ally?
Not to be the cantankerous grognard - Hey! You kids get off my lawn! - but you should search the RotRL forum for Nualia redemption threads. As of this writing, there are close to 53,000 posts in over 3800 threads in the nearly 10 years since the AP was first published. While there was a version change in the middle (3.5 to PF) many of the story and character questions like yours have been relevant since the beginning.
When you post an open question, you only get the benefit of those people who are currently watching the forum. But there is 10 years of accumulated... wisdom(?) buried within the those 50k posts.
As for Nualia, there are some redemption rules in Pathfinder though I am not familiar with them. In Champions of Purity I believe. I think there are some GM's who have done this with those rules or some they developed on their own and even a couple that have posted recently.
Less helpful aside...
For my part, I've always thought of Nualia as a whole lot of scorched earth away from redemption - she killed her adopted father, burned a good aligned church to the ground, hunted down and murdered the father of her stillborn child (he may have had it coming, but still...) became a cleric of the Goddess of Perversiona and Depravity, organized multiple assaults on Sandpoint, burned her father's bones in unholy sacrifice to begin her transformation to a succubus and plans on burning a town of 1200+ people to the ground to finish the process. At some point there is a "not coming back" threshold.
I played her with a "For hate's sake I spit my last breath at thee" attitude and my pc's were only too happy to oblige. :)
Thanks for letting me know! I'm new to Paizo threads, so I'm sorry if I'm a bit nooby around this page. I will make sure to search deeper in threads if I have another question. Thanks Latrecis you've been nice with your responds. See ya around, and happy gaming!
No need to apologize for being new or for asking questions. Just wanted to call out there might be answers or interesting information in the forum's history.
I debated responding since redeeming Nualia was not a path my version of RotRL took and I had little to add to the original question. Maybe someone who's pc's have tried to redeem Nualia will add a response.