Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Doctor resists mental parasite with desperate retreat
S15E6
·
The Invisible Enemy Part 2
To
Doctor exposed as virus carrier saves TARDIS
S15E6
·
The Invisible Enemy Part 2
Why These Connect
The narrative assertion
"The Doctor's initial mental resistance to the Nucleus (in Titan Base) sets up his later explanation of the virus' behavior and Leela's immunity while in the Isolation Ward at the Bi-Al Foundation. His firsthand experience of being targeted directly causes his subsequent analysis of the virus' modus operandi."
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot—remove one and the story structure collapses.