Board Thread:Questions and Answers/@comment-78.20.137.17-20131119192351/@comment-189.122.6.110-20140417161558

In MGS2, he really was possessed by Liquid's persona. However, he removed the arm to rebalance his psyche, and used drugs, therapy and nanomachines to assume Liquid's persona. So technically, he was possessed in 2 and self-brainwashed in 4