Board Thread:General Discussion/@comment-5475153-20140825213518/@comment-5475153-20140828044246

Like Abercrombie said, Bill was never banished, so he's still free to go anywhere he wants. As for the physical world thing, I've got my ideas. Whenever Bill shows up, the surroundings go monochrome, just like the mindscape. Could it be that Bill doesn't actually have a physical form, and that he instead just appears in other's minds? When Gideon summoned Bill, he--a conscious, sentient being--was the only thing that remained in color.

Of course, that does raise the question of how Mabel and Soos saw him, but he is "all-knowing" and probably knew they were there. He probably wanted them to see him, since he planned to use them to locate the code to Stan's safe for him later. True, Gideon hadn't asked him yet, but Bill makes it pretty clear he knows what others are thinking.

Now, the implications of Bill not existing in the real world are interesting: anyone who sees him could basically do anything they could wanted to him, since he's still vulnerable to imagination.