It's becoming clear the Sith have long attempted to create a Force Dyad - but Star Wars tie-ins have confirmed they are unable to do so. The mysterious bond between Rey and Kylo Ren was finally explained in Star Wars: The Rise of Skywalker, when the two stood before the Emperor. He recognized them as a legendary Dyad in the Force, a power greater than life itself, and he drained it in order to use its power against the Galactic Fleet.
Tie-ins have revealed the Sith have always been aware of the Force Dyad, and indeed have attempted to create one for millennia. The Sith language, ur-Kittat, is a notoriously tricky tongue, and a simple change in inflection can alter a prophecy or doctrine completely. According to the Star Wars: The Rise of Skywalker Visual Dictionary, the Sith Rule of Two is actually related to the Doctrine of the Dyad, with just a slight change in inflection binding the two together. This isn't just some abstruse point; rather, it suggests the Sith Rule of Two wasn't just established to restrain the dark impulses of the Sith, but also with the hope the close bond between Master and Apprentice could create a Dyad. Darth Plagueis attempted to create a Dyad with Sidious, and Palpatine tried to create a Dyad with Darth Vader. And yet, for all their effort and power, the Sith failed.
Tie-ins have since explained why. As seen in Charles Soule's The Rise of Kylo Ren, the Force Dyad is not something created by any Jedi or Sith; it is formed by the will of the Force itself, and indeed the Force Dyad shared between Rey and Kylo Ren was born at the moment Ben Solo embraced the dark side. Crucially, Rae Carson's novelization of Star Wars: The Rise of Skywalker adds more detail when it reveals the Dyad is strengthened and nurtured by both the light side and dark side of the Force.
"Rey watched her grandfather's dawning horror as he finally realized his mistake, allowing Rey and Ben to come together. Their bond - refined in the fire of mutual searching, shared grief, rage and hate, but also of compassion and empathy - was the one thing he had not foreseen."
The first Jedi were servants of balance, embracing both light and darkness, possibly even viewing balance as a separate aspect of the Force in its own right. In those early days, it is reasonable to assume Force Dyads were commonplace; but when the Jedi schismed and the Sith were born, the two factions forgot balance, each swearing themselves to one side of the Force. The Sith attempted to reproduce the Dyad using the dark side alone, but they could not do so, for it is associated with balance; the Jedi Master-Padawan bond was likely also an attempt to recreate the Dyad, but it too inevitably failed, because the Jedi only used the light side.
But knowledge of the Force Dyad remained. The ancient Jedi texts Rey studied contained details of powers of the Force only available to Dyads, such as the unusual Force Heal power she demonstrated in Star Wars: The Rise of Skywalker. Presumably the Jedi grew disinterested in the Dyad as time passed, simply because they never craved power; but the Sith remembered it, and longed to unlock its potential. It is ironic, then, that a Force Dyad played such a key role in bringing an end to the Sith in the Star Wars sequel trilogy.
