In the first season they figure out that the timeline is mutable. Also they figure out that there is a villian that is also a time traveller who has knowledge about the future and direct his minions with his foreknowledge.
When they change the timeline
(delay the plague)
the minions are suprised because the witness has not foreseen this.
But In the second season
there is very strong evidence that the witness even not only has foreknowlegde about all the changes our heros make but in fact has planned all that, because he awaits them in titan after a chain of events that involve mutliple changes of the timeline.
We have other instances where characters are somewhat outside the time and are not affected by timeline changes and are the only one who recognize the changes and remember how it was before.
But the witness seem not only to be like that and react to changes of the timeline, he seems to know what changes will happen (know the meta future of the whole timeline or something like that).
I'm at the end of season 2. Is there any explanation for this later? Is there any explanation why he gives his minions only "unchanged timeline foreknowledge" and not more?