My theory at the moment is that the dreams the PC has are not caused by the tadpole at all, but by a succubus/incubus. This would have to be a super special tadpole to seduce its host into accepting it when it could just eat the brain and have control. But a succubus's MO is seduction, and those dreams are most definitely seduction. So I'm trying to decide if the PC is a pawn for one side or a tug of war rope between both. Maybe I'm way off base, but a figure is standing over the PC the first time they sleep after using the tadpole, and I'm pretty sure it's a winged figure. Then, if you keep using the tadpole, you get a vision of looking over a city (I assume Baldur's Gate) that is half in flames. What purpose would that serve for the illithids? Guess I'll keep wondering for now.