Idea : You need someone willing to use them even if they aren't trustworthy
Just like those naive heros, he will get used by his party then eventually realize that his efforts are futile, then become bad once more
Rather, how can you explain their thoughts ? For it would just make the characters confusing and more mysterious, irl we don't hear other peoples thoughts, thats why we can still be suprised by their actions.
So yes it can make a great story, with providing more details like facial exspresion...