- "What you call subliminal is a Bellwether, Marcus. You've got a sharp eye kid. But subliminal is passive. The Bellwether program is control; its like a Orwell-Huxley double-punch. Profiling, media manipulation, corporate collusion, consumerism, all driven by predictive algorithms. And now, its setting up shop at the heart of the Silicon Valley and somebody at Blume's using CTOS to feed it data."
- ―Raymond Kenney to Marcus Holloway
Bellwether is a behavioral prediction system integrated in the CTOS.
Bellwether was stated by Angela Balik as she claimed that Raymond Kenney feared the Bellwether because it could influence people to echo a set of numbers, through the media surrounding them. Bellwether is also considered a form of mind control software. This is done by utilizing made-up memes, manipulating lyrics in famous songs & influencing the media. This in turn influences the way people think. This causes Bellwether to produce logically precise predictions for the future.
The Bellwether is able to program the system to target precise results, such as election results. The Bellwether was programmed by an Italian programmer known as Desipio to rig the elections. Bellwether is known to have been used two times on Dermot "Lucky" Quinn's order, one time to arrange the re-election of Mayor Donovan Rushmore and a second time to record him murdering Rose Washington, providing Quinn with blackmail on him and forcing the mayor to remain under Quinn's orders.
During the events of Watch Dogs 2, it was revealed that the CTOS 2.0 was using the Bellwether system to obtain personal information about people, and to enhance their system, using various tech companies such as Nudle, Tidis, and Galilei. This was led by Dušan Nemec, but in the end, Marcus Holloway and the other DedSec members (informed by Raymond Kenney) teamed up and exposed Dušan and the Bellwether system, resulting in the Bellwether being shut down and Dušan being arrested.
Parallels to real life
In reality, a bellwether is a trend-setter. The term originates from a Middle English term for a cow with a bell hanging from its neck, signaling people around potentially blind corners that a herd of cattle was approaching. Today, the term is used for anything that's perceived as a reliable trend-setter, like specific electoral districts that tend to consistently vote for the winning party, or a specific company's stock that tends to drag its entire industry along with it as it goes up or down. This is what is meant in the audio logs when the CTOS version is described as "not a typical bellwether model" - the typical bellwether is more an oddly consistently lucky guess, while the CTOS is actively exerting an effort to control the outcome.