Cole begins having nightmares of becoming the new Source. He tries to fight becoming the Source, but the Source keeps him from revealing what happened to the sisters, as the Seer attempts to guide him on his new dark path. However, Phoebe senses something is wrong with Cole, so she casts a spell to hear her heart's desire to help her decide if she should marry Cole, 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. Younger Phoebe reminded Present Phoebe of her favorite fairy tale, Cinderella, and her dreams of finding her prince. Older Phoebe admits to Cole privately she never married him; Older Phoebe then sacrifices herself to save Cole from a demon attack.[14] The spell reversed itself, and Phoebe decided to go through with the wedding.
Now fully controlled by the Source, Cole orchestrates a number of events to spur Phoebe to call off her wedding, in order to marry Phoebe in a demonic ceremony (which is disguised as a private ceremony).[15] Shortly after, Paige begins to distrust Cole. 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 her, nearly driving her insane, save 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.[16]
When a power struggle breaks out between Cole and the exiled 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.[17]
Phoebe indeed becomes pregnant (she doesn't know that her child is a child of the Source, and contains nothing of either Cole or herself) and she begins throwing fire and teleporting because of her baby's demonic influence. When Cole tries to convince Phoebe she is not turning evil, she finally gets a premonition revealing Cole is a demon, and she immediately leaves him.
Cole's love is now strongly affecting the Source, and Cole refuses to be confirmed as the Source; The Seer then goes to try to convince Phoebe to go back to Cole. When Cole is attacked by an evil wizard who schemes to seize the Source's powers, Cole offers to give up his position as the Source, and to transfer the Source voluntarily into the Wizard, as a final attempt to rid himself of evil power and win Phoebe back.[18]
However, during the transfer ceremony, the Seer makes Phoebe believe that the wizard is in fact killing Cole. With the Seer's coaching, 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 (Ironically, this is the second time Phoebe is the cause of Cole's becoming evil). Phoebe then joins Cole as his Queen, and the couple become the new rulers of the Underworld. After some mishaps; namely her killing off many upper-level demons, saving innocents and being tricked by the seer, Phoebe begins to doubt her role as the Queen of the Underworld. With Phoebe's loyalties torn between Cole and her sisters, Paige and Piper attack Cole, banking on Phoebe choosing the right side. Phoebe is forced to side with her sisters and vanquishes Cole and the Source's power with him.[19]
After being vanquished, Cole and the Source finally end up as separate beings in the astral plane of the demonic wasteland (where demons usually go after being vanquished). The powers of the Source, however, were inherently duplicated/embodied in the demonic child and heir of the Source. With Cole gone, the Seer was free to steal the demon spawn from Phoebe's womb and seize power as the new Source, which was her plan since the previous incarnation of the Source summoned the Hollow. Subsequently, the Seer was overwhelmed by the Source's power, just as Phoebe was, and the sisters turned that to their advantage, causing the Seer to explode and vanquish the entire demonic court.
As Cole was born a half-human (Cole)/ half-demon (the now vanquished Belthazor) being, Cole has a human soul, whereas pure blood demons have no souls. This is "rather unique to the cosmos," as Cole puts it. Cole 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).
