So, a few funny happenstances cascaded in my Sneed playthrough.
I decided to be a good Durge this game.
I saved the grove and the druids and recruited Halsin.
Saved Minthara too and currently romancing her.
All seems good until...
I decide not kill Isobel at Last Light Inn. Resisted the Durge.
When it came time for Marcus to kidnap her, I killed him.
However, one of the ghouls wound up paralyzing her while another killed her.
Last Light Inn was destroyed.
Jaheira demands to know what happened and I tell her the truth.
Jaheira dies to the shadows.
I think the Shadowlands is screwed, but Halsin tells me I can just talk to the dude's corpse and get the info about Thaniel there.
We save Thaniel.
LLI is fallen, but I can still remove the Shadow Curse. Who'd a thunk it?
But here's where it gets hilarious...
Long rest and Durge wakes up. I didn't kill Isobel so I gotta kill my romance partner.
...except the whole cutscene skips!
Later I talk to Minthara and she's like, "Good job resisting, but don't let it happen again."
WTF?!
Much later I fight Ketheric and Isobel is there, under his control.
I focus all attacks on Ketheric, leave Isobel alone. Maybe I can save her!
Avatar of Myrkul is dead! Now if I can just knock Isobel out...
Nope!
Isobel just dies on the spot. Bleargh!
Game thinks I killed her.
Next long rest on the way to Baldur's Gate, narrator says
I murdered Isobel.
My butler arrives, congratulates me, and I get the Slayer form!
WHAT?!
Eager to see how the rest plays out in Act III.