I never trusted him from the get go. There was always something off with him. There are a bunch of things that coulda happened.

1.) He is possessed. This is a favorite of mine, however I don't know how Bill would be able to possess Ford and go to Gideon without leaving his vessel. So, there are major kinks in this one.

2.) He is plain crazy. By crazy, I mean worse than McGucket crazy. He was in the portal for thirty years, while McGucket was there for a few minutes. He almost shot his brother with a crossbow for crying out loud! And screamed 'Are you here to steal my eyes!' On an unrelated topic, he might have been confronted by the newly formed Society of the Blind Eye. Because they 'take' your eyes.

3.) I've seen something that had to do with brainwashing when he was in the other dimension. But, I'm not sure about that one. Seems kinda far fetched.

He did say trust no one, so we can't even trust him.

Well, that's all I can think of right now. Please comment your ideas on Ford's sanity.