I can agree that the character should be given the opportunity to make his own decisions, but I would also like the level of ability check to change depending on our behavior.
If I act out evil, kill children in the druid grove, do all sorts of bad things and all the time I want more power for myself, and therefore in order to persuade Astarion to refuse ascension I need to roll 20-25 charisma, because all my actions in Acts 1 and 2 were nagging him to such behavior.
Or if I save everyone all the time and show by my example that it is not necessary to manipulate people to achieve results, 5-10 charisma is enough for me.
It seems to me that adding such a check on the behavior of the main character would have better played on the atmosphere of Astarion’s final quest.
