The Yoko Factor (plan)

"The Beatles were a very powerful group. It's not a stretch to say that they pretty much ruled the world. When the group broke up, everybody blamed poor Yoko. The truth is, the group broke itself up. She just happened to be there."

- Spike describes the concept of the "Yoko Factor" to Adam

"The Yoko Factor" was a divide-and-conquer scheme enacted by Spike to split up the Scooby Gang in early 2000.

History
After allying with Adam to get the Initiative's anti-human aggression chip out of his head, Spike came up with a plan to split Buffy and the Scoobies apart from one another, deeming it "the Yoko Factor" in reference to Yoko Ono, who was blamed by many for the breakup of the Beatles, as part of Adam's master plan.

Using the existing tensions between the Scoobies to his advantage (Buffy's intense focus on her newfound relationship with Riley, Giles' feelings of uselessness, Xander's lack of direction, and Willow's recent gay relationship with Tara), Spike paid visits to Willow, Xander, and Giles, playing on their insecurities and strained relationships to successfully turn them against one another.

However, in a subsequent encounter with Spike, Buffy put two and two together when Spike let too much information slip, and reunited with her friends to stop Adam. While sneaking into the Initiative base, Buffy, unsettled by how easily Spike had turned them against one another, and not wanting to lose her friends, reconciled completely with the rest of the gang.

Appearances

 * "The Yoko Factor"