Board Thread:General Discussion/@comment-25548156-20130814194325/@comment-24212799-20160109151345

In "Dreamscaperers" we already saw Bill gaining access into Stan's mind effortlessly and tricking Dipper and the others into believing he was Soos. I wouldn't be surprised if he snuck into Blendin's head disguised as Time Baby or something and tricked him into gaining access into his soul.