In almost any narrative, whether factual or fictional, a causal sequence is also a linear temporal sequence. A caused B and also preceded B. Of course. We are so used to the identity between these two sequences that we expect it to continue even in a narrative featuring time travel.
In Neil Gaiman's The Books Of Magic: The Road To Nowhere (New York, 1991):
(i) Tim Hunter departs into the future with Mr E;
(ii) they fail to return;
(iii) increasingly concerned, E's colleagues send Tim's owl into the future to help him;
(iv) Tim returns...
(v) ...having been helped at the end of time both by the owl and by Death of the Endless.
(i)-(v) is an objective chronological sequence although, in Tim's subjective experience, (v) precedes (iv). Hence, the otherwise nonsensical phrase, "...having been helped (perfect tense) at the end of time (in the future)..."
We automatically accept that (iv) follows (iii). However, if Death had returned Tim to his starting point, then:
(i) Tim would have returned as he and E departed;
(ii) Tim would not have failed to return;
(iii) E's colleagues would have had no cause for concern and would not have sent the owl;
(iv) Tim would not have returned later;
(v) He would have been helped at the end of time only by Death.
However, Death saw the owl arrive in the future and therefore knew that she had to return Tim not to his starting point but to after the owl's starting point. This is circular causality: the owl was sent because Tim had not returned immediately and Tim had not returned immediately because the owl was sent.