Board Thread:General Discussion/@comment-6905051-20131203105732/@comment-1894786-20140917180121

I think that the potion only erased the knowledge that the Savior was Henry's mother. In "Pilot", when Regina first meets her, she's very kind and welcoming. Sends her on her way with a drink. The next day, after she spots Emma in Graham's cells, that's when she starts being downright nasty. My guess? The potion wore off the night Emma spent in jail, which is why Regina went full-on Evil Queen from then on.