For me, they should have show that by taking away some choices (showing them in grey but not allowing to pick them) the more tadpoles you consume and the more illithid you have become. Since you are no longer you. But it is just my take.
That would be an improvement. I could also come to like - or rather learn to love to hate - the emperor if:
1. Tav had any good lines
2. Your words had any impact
The idea that you working with a master manipulator with a god level charm skills is good set up for a villain. But we never really get a scales drop from our eye moment. Instead we listen to him speak and our responses boil down to: "please say your next line now"
Compare this with Shadowheart who has meaningful responses to critical questions and your responses really do alter the relationship. Having romanced Shadowheart twice I decided to take a hostile tone in my current run. "Whatever Sharran" And now she's dead: Lae'zel and I were forced to kill her. I feel bad for her.
Something that would have been fun would be if Raphael could have given us something that broke the illithid charm and allowed Tav to ask challenging questions.
Raphael: ". . . very well, I'll be here if you reconsider. But, before you leave, please accept a parting gift. If you feel tongue tied when speaking to the illithid say the words "purgare animum meum" and even the strongest charm will be broken. I think you'll find that the cat has your tongue. And his claws have dug quite deep.
