I imagine that the ones you don't take to Moonrise are turned into Mindflayers in the interim. As soon as you check in on the camp, the ones remaining just spontaneously turn, just like the people on the nautiloid. Giving us a good fight, a deadly reminder of the risks of not finding a cure, and ensuring the other residents of the camp don't get killed. If fighting mind flayers at this stage is too tough then they just leave. Talking to other NPC's at the camp they explain that they got a weird look in their eyes and just left without warning or notice. They return later in the game as minibosses, completely controlled by the Cult of the Absolute. Either as themselves just as enemy NPCs or as Mindflayers.
Enjoying having a walking nuke formerly known as Gale in your headquarters Octopus brains!
I and my team or morally ambiguous team of me Human Wizard, Astarion, Lae'zel, and Shadowheart shall morn our lost companions in our hearts.
The thing is, that is not compelling to me at all. In fact it feels kinda cheap and pointless. And also really highlights the issue of unjustified things like small party size.
