Early history

Cole was born in 1885 to California state assemblyman Benjamin Coleridge Turner and a demon mother named Elizabeth. Benjamin was murdered by Elizabeth in 1888 and, after Cole's birth, his mother took him from Earth and raised him in a demon dimension. Cole grew up despising his human side for its weakness, and he became a powerful demon with a reputation as a killer under the name Belthazor.

Cole became a member of the Brotherhood of the Thorn, who served the Source of All Evil. He made a reputation for himself as an assassin who could kill any witch, an athame being his weapon of choice. Cole was hired by the Triad to get close to and kill the Charmed Ones. To do so, Cole returned to Earth in his human guise and was set up as an assistant district attorney in San Francisco.

Agent of the Triad

Cole first meets the Halliwells in the season premier of Season 3, in which he investigates the attack on the sisters' friend Morris. Because the sisters witnessed the attack and foiled the assailant, Cole calls the sisters in as witnesses for the man's trial. We don't learn that Cole is a demon until the end of this episode, in which Piper freezes the innocents in a courtroom and Cole is immune. He shimmers away and kills the demonic judge who has been assigning guardians to criminals. Within the next few months, Cole becomes very close to Phoebe and they begin dating. After his first few attempts to assassinate Phoebe and her sisters, he starts protecting them so that his assignment can continue. Eventually he stands up for the sisters and protects them, even though they do not know that Cole and Belthazor are the same person. Cole and Phoebe both fell in love.

During this time Belthazor is possessed by the demon of Rage, Andras, and he is forced to try to destroy the sisters. Belthazor vanquishes Andras, but is wounded by the Charmed Ones, who are able to create a vanquishing potion from Belthazor's flesh. At this point, the Triad attempts to kill Cole. Cole turns on them, supposedly killing them in the process before fleeing back to his apartment to recuperate.

When Phoebe goes to see Cole at his apartment, she finds that Cole is wounded and calls Leo to heal him. Leo tries to heal him but realizes that something is terribly wrong when he finds that he can't heal all of him, only his human half. At this point, Phoebe discovers that Cole is Belthazor and that he refused to kill her because he loves her. When Prue and Piper, who are working with a demonic bounty hunter, break in to Cole's apartment, Cole grabs Phoebe and shimmers to the mausoleum, proclaiming his love for her. Heartbroken, Phoebe fakes Cole's death to keep him from being killed by her sisters and tells him to run.

Demon outlaw

Cole does not return until Prue is put under a spell and married to a warlock in order to contaminate all the sisters, and the Book of Shadows, with evil. He claims that he is no longer going to be evil and that he can repress his demonic half in order to be with Phoebe. Phoebe goes to Cole for help in finding Prue, all the while telling him that she doesn't want anything else to do with him.

Phoebe and Cole grow closer as he helps free her from a psychic link with a Native American who was cursed in a time loop. Cole returns and becomes the Charmed Ones' demonic ally, working alongside them. He even witnesses Piper and Leo's marriage.

While at Prue's funeral, Cole is attacked by two demon bounty hunters but he quickly kills them. Later on, he discovers that the Source has sent a Chameleon demon named Alastar to spy on the Charmed Ones. Once uncovered, Alastar is attacked by the sisters and flees. The Source kills Alastar and takes his place as the sisters hunt him down. The Source then kidnaps Piper and takes her to the Underworld, where he uses his mental powers to create a fantasy world where Piper is a mental patient, hoping to trick her into giving up her powers to him. Cole and Leo travel to the Underworld to track down Piper while Phoebe and Paige use a spell to project themselves into Piper's mind. As Piper is about ready to relinquish her powers, Cole attacks the Source repeatedly with energy balls as he stands immobile controlling Piper's mind. Cole is eventually able to wound the Source, but as he attempts to kill the Source his attack is blocked by the Source's Oracle, who dies so the Source can escape.

Some time later, the sisters become aware of a demon who is killing witches. After Piper scries for the demon from slime they find, Phoebe and Cole attempt to track the demon down. They are attacked by a Scavenger demon, which is feeding on the remains left by the killer. It is at this time that Cole asks Phoebe to marry him in a spur of the moment. When Cole has to embrace his demon side in order to defeat another demon, a potion is used on him to strip him of his demon side, leaving him merely human.

Cole becomes human

Shortly after Cole becomes human, Cole and Phoebe are possessed by the spirits of Frankie and Lulu, a criminal couple who find their way to the present through a time portal. They go on a crime spree, stealing a diamond ring and a wedding dress, all so they can get married. At the church, Cole is shot and Frankie's spirit escapes, only to be captured by a spirit named Clyde and sent back in time through the time portal. Then Phoebe accepts Cole's marriage proposal.

Later, the Seer betrays the Source by contacting Cole and giving him the Hollow to help defeat the Source. The Seer and Phoebe then use their combined abilities to put the Hollow back in its crypt and return Piper and Paige's stolen powers. Following the Source's death at the hands of the Charmed Ones, his spirit slowly begins to take possession of Cole, infusing him with the Source's powers.

Cole as the Source

Cole starts having nightmares of becoming the new Source. He tries to fight becoming the Source, but it keeps him from revealing what happened to the sisters, as the Seer attempts to guide him on his new dark path. Phoebe casts a spell to hear her heart's desire, which summons her future and past selves to the present. Older Phoebe refuses to tell Phoebe about the events of the future for fear of changing things for the worse. Learning a young and vulnerable Phoebe is in the present, the demon Kurzon attacks Young Phoebe, but Cole protects her. Kurzon attacks again, this time wounding Older Phoebe. He is vanquished by the Charmed Ones, but not before Older Phoebe tells Phoebe to marry Cole. This returns the older and younger versions of Phoebe to their own time.

Now fully controlled by the Source, Cole orchestrates a number of events to spurn Phoebe to call off her wedding, in order to marry Phoebe in a demonic ceremony (which is disguised as a private ceremony). Shortly after, Paige begins to distrust Cole, and Cole hires a power broker to imbue Paige with a demonic power in order to distract her and her sisters so he can impregnate Phoebe with his evil spawn. Once alone with Paige in the manor, Cole plays mind games with Paige, nearly driving her insane if not for her sisters' intervention. At the last moment Cole gains enough control from The Source to save Paige by having other power brokers take the power out of her.

When a power struggle breaks out between Cole and the Queen of the Vampires, the Vampire Queen sends a group of vampires to bite Paige and make her a vampire under her thrall. Although they are successful, Cole is able to kill the Vampire Queen before Paige is fully converted into a vampire.

Cole is attacked by an evil wizard who schemes to seize the Source's powers. Cole offers him to give up his position as the Source voluntarily, as a final attempt to rid himself of its evil influence. However, guided by the Seer, Phoebe uses her baby's powers and kills the wizard before the power transfer can be complete, nullifying Cole's final effort to become good again. Phoebe then joins Cole as his Queen, and the couple become the new rulers of the Underworld. With Phoebe's loyalties torn between Cole and her sisters, Phoebe eventually chooses her sisters and vanquishes Cole and the Source's spirit with him.

After being vanquished, Cole and the Source finally end up a separate beings, in the astral plane of the demonic wasteland (where demons usually go after being vanquished).

As Cole was born as a half-human (Cole) and a half-demonic (the now devoured/consumed Belthazor) being, Cole has a human soul, whereas other native-born demons do not have a human soul. This is "rather unique to the cosmos", as Cole later tells Phoebe. Cole also has no inherent demonic powers in the demonic wasteland, as he was fully human when he was possessed by the Source (after the Source's previous body was vanquished).

The ancient demon who was originally was the Source, who had possessed Cole, is now finally truly dead and gone, devoured/consumed by the serpent-like beast of the demonic wasteland (as Cole also later tells Phoebe).

The powers of the Source however, were inherently duplicated/embodied in the demonic child and heir of the Source. Those powers were eventually controlled by the ancient Seer (after the Seer teleports the demonic child of the Source from Phoebe's womb into the Seer's womb, in "Womb Raider"). The combination of the Seer's own inherent powers, the ever-growing powers of the child of the Source, and the amplification of all those powers by the "Coronation of the Source" ceremony, is also clearly massive raw demonic power beyond what most magical beings could survive containing (as seen in "Womb Raider").

Cole's return

Although he tries to get Phoebe to help bring him back to life, Phoebe refuses and asks him to move on. Cole, now without hope, initially decides to meet his fate, but in the last minute learns how to absorb the remnant energies of vanquished demons. Cole quickly gains demonic powers and seeks redemption again. He comes back briefly to save Phoebe from a bullet, by switching her position with that of the witch hunter. He tells her that he isn't giving up on them. However, Phoebe and her sisters aren't about to accept him as their friend anymore. He comes back just as Phoebe is about to get a divorce, and she tells him it is over. Later he talks to Darryl who convinces him that if he loves Phoebe, he should go away, and he finally agrees. However Paige intervenes thinking Cole might be able to save Phoebe, who was heartbroken and wanted to become a mermaid. He disagrees but Paige casts a spell to show him how much Phoebe loves him. He goes to save her, and helps her turn back from a mermaid. But even though she says that she still loves him, she declares that their relationship is still over.

For a while he tries to prove that he is still good so that Phoebe will take him back. He saves a future Whitelighter from a fire, and is hailed as a hero, by all but Phoebe. Again and again he does good deeds only to be rejected each time by Phoebe on the grounds that his powers and his nature are evil and it would only be a matter of time until said evil powers betrayed her, and by proxy, his goals. Her fears were justified when he was seduced and kissed by a siren and still survived; Phoebe had arrived at the scene and was about to vanquish the siren when Cole, overcome by the very evil she warned him about, destroyed the vanquishing potion, kissed the siren, and turned against Phoebe, strangling her to near death.

Eventually, after being alone for many months, Cole gradually goes insane, due to the huge amount of demonic powers he took into himself in the demonic wasteland, and his despair over Phoebe's continued rejection of his love, no matter what good deeds he does. He decides he wants to end his life, since he can not be good and he won't be evil. He believes that the Power of Three is what is necessary to kill him again.

However, he learns that he has become invincible. Cole is now unvanquishable by any power, including the Power of Three's spells or potion (part of why the Avatars of Force and Power wish him to join their collective power). Cole then tries to kill himself over and over, even trying to behead himself (stopped for the moment by Piper freezing the blade that was about to sever his head from his body), but that also would not have killed him. Having gone completely mad, Cole then decides to team up with demons to help him bring Phoebe back to him, and with every attempt, he loses.

Cole as an Avatar

Cole joins Alpha and becomes an Avatar, a powerful being that is neither good nor evil, and corrupts reality so that Paige is never found. However, Paige catches a cold, and every time she sneezes, she orbs into a void, outside of space and time where beings like the Avatars live. So, Paige sneezes at the exact moment Cole changes time. Paige discovers his evil intentions and, with the help of Piper and Phoebe, vanquish him once and for all, or so it seems at the time. It was his 117th birthday on the day he is killed. 

Cole's afterlife

Instead of going back to the Wasteland, this time Cole ends up in the "void between life and death". It is here that Piper bumps into him after being attacked by a Thorn Demon and is hovering on the brink of death. Cole explains that he is there to help Piper get Leo back after he is taken away by the Elders to be punished for his joining the Avatars. Although Piper is wary of him at first, she soon realizes that Cole is right and takes his advice. In the end, Piper and Leo are reunited.

Cole also says that he wants Phoebe not to give up on love and wants her to move on. It is revealed that Cole was the one who arranged for Drake to become human and meet Phoebe, and arranged Piper's attack from the Thorn Demons. How Cole managed to accomplish this remains a mystery. Nor is it clear just what kind of being Cole is now. When Piper asks if he is a Demon, ghost, poltergeist, or spirit, Cole said he is none of those things, but did not specify further. His ability to influence the Thorn Demons, communicate with Drake, appear in Magic School and teleport at will implies that he may well be alive.

But when The Charmed Ones retire and the next generations take over, there appear to be no signs of Cole. An optimistic look at his last episode could suggest that he has finally found at least some inner peace and redemption.

Powers and abilities

As Belthazor, Cole is a demonic soldier of fortune. He is an upper level demon and it requires a potion which uses a piece of his own flesh to vanquish him. He can shimmer, throw energy balls, and he possesses super strength.

Cole eventually becomes The Source of All Evil, and theoretically possesses most or likely all of the powers of the The Source, including teleportation, fireballs, force fields, lightning bolts, pyrokinesis, shapeshifting, telekinesis, summoning, mind control, and possession.

During his time in the Demonic Wasteland, Cole learns that the serpent of the Wasteland feeds on the powers of vanquished demons. In taking the powers before the serpent is able to, he eventually defeats the serpent, or at least destroys parts of it, making him able to obtain however many powers are available. Since Cole returns from the Wasteland within 72 hours of Phoebe travelling to the Wasteland, and the fact that we only see about ten different powers used on screen, the actual number of powers may be as few as ten or well in to the hundreds or thousands. However, the exact number or type of powers is impossible to determine. Cole is seen on screen using teleporting, telekinesis, energy ball throwing, conjuring, lightning bolts, molecular manipulation and can grant invincibility to other demons for a time, invincibility, and some time control (we can assume that his time-related powers are not vast, as he must go to the Avatars in order to change reality).

As an Avatar, Cole possessed ability to change reality. Given the nature of Avatar powers, however, we can conclude that Cole's powers were virtually unlimited, and included, but were not limited to, energy waves, lightning bolts, power containing, the ability to create illusions, time control, the ability to remove people from existence, resurrection, and teleportation.

However, when he changes reality, including his own physical history, to be with Phoebe, he loses his Avatar powers, in addition to his powers from the demonic wasteland. Cole ceases to be physically immortal, and reverts having to only having the demonic powers of Belthazor, without actually being the dual Cole/Belthazor human/demonic being (not that the other demons in that alternate reality are aware of this, but a reference is made to the Seer about possibly reporting him to the Source, for his "slightly off" behaviors). Cole is therefore rendered vulnerable in that alternate reality, to anything that would have harmed or killed Belthazor, which the leader of the Avatars warns him about, in an attempt to get Cole to reverse his changing reality spell