  We introduce a novel method for analyzing person-to-person content influence
on Twitter. Using an Ego-Alter framework and Granger Causality, we examine
President Donald Trump (the Ego) and the people he retweets (Alters) as a case
study. We find that each Alter has a different scope of influence across
multiple topics, different magnitude of influence on a given topic, and the
magnitude of a single Alter's influence can vary across topics. This work is
novel in its focus on person-to-person influence and content-based influence.
Its impact is two-fold: (1) identifying "canaries in the coal mine" who could
be observed by misinformation researchers or platforms to identify
misinformation narratives before super-influencers spread them to large
audiences, and (2) enabling digital marketing targeted toward upstream Alters
of super-influencers.
