I said antagonistic not antagonist. He may not transform into a villainous figure, but he will not stand for the mistreatment/elimination of the parshmen. Many will actively seek to destroy them it would not surprise me if he actively fought against those who would destroy them which may at some point include Shallan and Jasnah. I would not say that he will be evil, but he will fight back I think because the sum of his experiences including those with Rlain will leave him unable to stand by and do nothing.