When considering the Impact Character's Throughline, look at their identity in terms of their impact on others, particularly the Main Character. Think of the Impact Character in terms of his name, but it's the name of someone else, someone who can get under your skin. In viewing the Impact Character this way, it is easier to identify the kind of impact that he has on others. Obi-Wan Kenobi's fanaticism (on using the force) in Star Wars and Deputy Marshal Sam Gerard's tenacity (in out-thinking his prey) in The Fugitive are aspects of these Impact Characters that are inherent to their nature. These qualities would continue to be so in any story in which they might be found.