I thought Katarina had also remembered an alternate past?Well they "could" do that, but then you wouldn't have the setup we have for next season. There also wasn't really enough time for them to do that in this episode. He would have only been able to drink the tea after that event already happened (to him). He made a rash decision (as he does) to make the jump forward after Cassie. They would have needed to pause, think hey I can drink the tea, go find the red leaves (remember the storms/red forest had receded/healed itself) to make the tea. In order to be sure, he would have had to jump BACK in time, to "tea jump" forward. That's a lot to pack into what 5 minutes of screen time.
Have to say I really enjoyed the finale and look forward to what do next season. While this show just for really complicated, the writers this far have always "covered themselves".
As far as the Witness being Coles kid, we assume it is, it's heavily hinted it is, but we can't be 100% sure due to the changes that were made. We know there were changes made (major ones) as Cole was surprised Cassie remembered the butterfly. That was a 1st (someone outside of Cole remembering the "alternate" past. This may be the hint that the child IS Cole's. Throughout the series Cole has been deemed "special". He's also the only real person that can continually time jump without dying. I believe there were small comments made saying the Witness resides "outside of time" of this is the case then that may be the reason Cassie can remember the alternate history. She is being affected by being pregnant with the Witness. This would also explain how The Witness knows what they do. Residing outside of time would allow for a "total" view.
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