Ok, explain this to me. At one point in camp, Lae'zel approaches you as you feel really sick.
She suspects you are turning. You have no reason to doubt it, and one of the dialog options is "Succumb to Lae'zel..."
If you do this, she kindly puts you out of your misery. Cut scene ends, you are dead back in camp.
But as you can be resurrected by others, it's not game over! However, Lae'zel then leaves the party as the others start to gang up on her for offing you. A fight ensues.
She runs to Shadowheart first. My party is down to three: Dead me, Shadowheart, and Gale way over thataway. He's not even joined the fight.
Just for fun, I have Shadowheart cast +2 AC on Lae'zel. Lae'zel kills her next round.
But Astarion runs over. He dashes and arrives. Shadowheart is not dead quite yet.
Astarion lost condition Dash.
Shadowheart failed a death saving throw.
Shadowheart succumbed to death.
(Lae'zel just dies when Astarion, not in the group, takes a swat on her.)
Lae'zel fell to a lethal blow.
That's the entire combat log.
The question is: HOW? She had full health and max AC and +2 at that for my party! There is nothing in the log about Astarion's attack at all. Astarion had his simple dagger he comes with, nothing more.
Lae'zel Level 3, AC 17 (no +2 AC) but 31 hp!
Astarion Level 2, as a campy I didn't even fully level him, attack damage 1d4 + 3 for DEX. So even if he crits, it's what, 14 max damage. That doesn't even get him to half way to Lae'zel's hp.
I assume for now it's just a programmed result from something akin to a cut scene, a robo-controlled, non-party member in camp.
I guess letting Lae'zel wipe the entire party is not an option. Rats!
Though from Internet analyses I've seen, she's one of the few who could carry the mission through to the end. There's a fun video of what if there were no TAV, and no companion as an origin story, just what likely would happen to each as they struggle against the fates.