Power of Three (Charmed)

The triquetra as shown on the Book of Shadows

The Power of Three, on the WB series Charmed, refers to any bond formed by three magical beings good or evil. It is most commonly used to describe the bond between the Warren/Halliwell line, more specifically the Charmed Ones, which is said to be the most powerful magical force in history.

To my three beautiful girls. May this give you the light to find the shadows. The power of three will set you free.

— Inscription on the Halliwell spirit board

It is not explicitly stated how a Power of Three bond is formed however. Melinda Warren - the first witch seen in the Warren/Halliwell line prophesied the birth of The Charmed Ones when she was burned at the stake, "With each generation, the Warren witches will grow stronger and stronger - until, at last, three sisters will arrive. Together, these three sisters will be the most powerful witches the world has ever known."

Connection

The Power of Three refers to the combined powers of the Halliwell sisters which is noticeably stronger than their individual powers. During the series' run the sisters were able to protect themselves against powerful spells and destroy many demons when using their combined powers. This can be seen in the first episode as the sister's battle a warlock and are able to protect themselves against fire and destroy him by chanting "the power of three will set us free". While some spells require the Power of Three to take enough effect, it isn't always necessary for all three sisters to chant a spell together, only as long as they are all together at the same time.

This power was also shown to connect the sisters on both emotional and magical levels. Certain spells cast on one member can affect the others. The most notable instance of this occurred when Prue is turned evil by a spell that eventually spreads to both Piper and Phoebe. Also, in the episode "Power Outage" a demon manipulates the sisters into fighting and using their powers against each other resulting in them losing all of their magical powers. It is only through mending their relationship that they are able to retrieve their magic. It is also revealed that their powers are greatest when in their home Halliwell Manor with the Book of Shadows. The Power of Three, the ancient magic and bond that is imbued with the sisters, is represented by the ancient symbol called the triquetra. An embossed triquetra was placed on the front of the Book of Shadows and would split whenever the Power of Three was split.

First Generation

The original Charmed Ones. From left to right: Phoebe, Piper and Prue.

After three centuries, the prophecy was fulfilled by the birth of Prue, Piper, and Phoebe Halliwell. The sisters use their powers to protect innocent people and fight various warlocks and demons, often invoking their joint powers to defeat their enemies. Eventually, the sisters not only developed strength, but also willpower and an unusually strong bond with one another, enabling them to stand united despite their very notable differences. Their magic is rooted in their bond as sisters and as a family. This is shown through flashbacks in the episode 'Prewitched' as their grandmother struggles with whether or not to release their powers because the sisters do not get along.

Each sister's own powers grow as the series goes on to the point where they develop new ones; Prue develops astral projection, Piper gains molecular combustion whilst Phoebe is able to levitate. As these powers appear their joint power as the power of three also appears to strengthen.

Second Generation

Phoebe and Piper meeting their new sister Paige.

With Prue's death in 2001, the Power of Three was shattered. However, hope for its reconstitution was brought by the arrival of Prue's, Piper's, and Phoebe's long-lost half-sister, Paige Matthews. Paige was the result of a forbidden, clandestine love between Patty Halliwell, the mother of the sisters, and Sam Wilder, her Whitelighter. The Power of Three was then able to reform itself with Paige's arrival.

Other Variations

The Power of Three has also been seen in other forms throughout the season. For example, in "That 70s Episode", Patty casts a spell with young Prue and Piper as she is pregnant with Phoebe at the time. In another occurrence, Penny, Patty, and Piper used the Power of Three to banish the Hollow in the final season.

Any three people possessing each of the Charmed One's powers through their blood or a 'To Call a Witch's Powers' spell can form their own Power of Three, provided they can stop the original users from channeling it in the first place. The Stillman Sisters exploited this for their own ends when impersonating The Charmed Ones.