On the Season 4 Episode 21 of Grimm:
We see the possessed Sean Renard continue killing Portland's ladies of the night. But in that same episode, we see him kill Henrietta. Why did Renard-the-Ripper kill Henrietta? She didn't seem to be any threat to him, as she claimed to not have any knowledge of what ailed him. Furthermore, Henrietta was hailed as an all-powerful, all-knowing Hexenbiest; how did Renard kill her so easily? She should have seen him coming from a mile away.