In the original timeline of Season 3, we know there's a war between the two universes, that Olivia crosses over to save Peter, gets kidnapped, and Fauxlivia impersonates her in the Over Here universe. When she gets discovered, a lot of the animosity towards her is caused by the fact she slept with Peter, in a classic "mistaken identity/evil twin" trope.
However, in the revised timeline of Season 4, there was no Peter. We still know the war between the two universes happened, and we're told Olivia still got kidnapped and replaced by Fauxlivia.
My question is: is that all Fauxlivia did? Just impersonate Olivia? Why does everyone on the Fringe team still seem to hate her, then? Walter calls her a "viper" and a "prostitute" (in his humorous roundabout way). Why would Walter consider her that, if the whole deal with Peter never happened?
I realize this was probably just a throwaway joke, and the hatred didn't last long anyway, but maybe I missed something...