The Letter C

In 2000, Prue, Piper and Phoebe Halliwell were sent back into the 1670's by the elders in order for them to save a pregnant, kidnapped Charlotte Warren who actually turned out to be one of there descendants. After the Sisters meet up with a coven of witches who needed their help, they go to a festival in front of Ruth Cobb's house, a mortal who practiced the black arts of magic and who kidnapped Charlotte. Unknown to them, Cole Turner has also traveled back in time as well, to stop them. As the masked sisters join the festival, an Irish man approaches Phoebe and offers to show her the first letter of her true loves name. When Phoebe blow's onto the apple peel, Cole arrives. She drops the peel into the bucket of water; the peel show's C. At the time, It was was thought to of meant Cole as cause they were romantically involved before and after Phoebe found out he was a demon. They got married towards the end of Season 4, but were forced to vanquish him after he became The Source of All Evil. Although he return again the next year, he had to be vanquished again, after he created an alternate reality where Paige didn't exist. It wasn't until the end of Season 8, that the C represents, Coop - A cupid that Phoebe fell in love with, married and had three daughters.

There were also other theories to which the C represent.

Clay Rivers
Early in the show, Phoebe's former boyfriend Clay Rivers came to town after helping steal a cursed urn in Egypt. He tried to have Prue auction it off, but when she learned it was stolen she had it removed from the auction. The Guardian of the Urn attacked Clay, but an act of selflessness in saving Phoebe redeemed him and the Guardian disappeared.

Cole Turner
She started a romance with district attorney Cole Turner, who turned out to be a half-demon named Belthazor, sent to kill the Charmed Ones. Although Cole had started out using her to get close to the sisters, they fell in love. When Cole's demon half was revealed to the Charmed Ones, Phoebe helped him fake his own death and then let everyone, including her sisters, believe he was dead. Phoebe then spent time researching Cole's past, confiding only in Leo that she did not really vanquish Cole. Phoebe eventually told her sisters the truth, and they soon accepted Cole into their lives. A few months later, Cole proposed.

While Cole started getting nightmares of becoming the new Source, Phoebe started to get a bad feeling about her upcoming marriage, so Piper suggested she use magic to find out what her heart felt. Phoebe cast the spell to hear her heart's desire, which ended up summoning her future and past selves. Older Phoebe refused to tell Phoebe about the events of the future for fear of changing things for the worse. Learning a young and vulnerable Phoebe was in the present, Kurzon attacked young Phoebe, but Cole protected her. Leo took little Phoebe to the realm of Whitelighters for protection. Kurzon attacked again, wounding older Phoebe. He was vanquished by the Charmed Ones, but not before older Phoebe told Phoebe to marry Cole. This returned the older and younger Phoebes to their own time.

Phoebe and Cole married, and Phoebe became pregnant. With the pregnancy, she began manifesting the ability to shoot flames from her hands and to teleport. Cole attempted to give up his position of Source of All Evil to an evil Wizard, but failed when Phoebe used her baby's powers to kill the Wizard. She then joined Cole as his queen. Phoebe tried to live the life of evil, and a combination of hormones and demonic potions made her so cranky, she ended up vanquishing five of Cole's best Demons. Then she tried to play both sides of Good and Evil, but realizing she could not, Phoebe rejoined her sisters in opposing Cole. Together they cast a spell which used the power of their ancestors to vanquish Cole.

After Cole died, he ended up in the Demonic Wasteland, where all Demons go after being Vanquished. His Powers as The Source were absorbed by the creature there, but he survived by clinging to his love for Phoebe. Although he tried to get Phoebe to help bring him back to life, she refused and asked him to move on. When Cole learned he could absorb the powers of other demons when they were killed in the Wasteland, he collected an impressive array of abilities and escaped, just in time to save Phoebe's life.

Phoebe was transformed into a mermaid by a spell, but was turned back when she admitted her love for Cole. Phoebe told Cole that while she did love him, their relationship was completely over and pushed through with trying to obtain a divorce. Despite Cole's efforts to pursue her, Phoebe realized how dangerous their relationship could be and tried to move on with her life, by dating other men.

In one final effort to win Phoebe back, Cole cast a spell which altered reality, making it so that the Power of Three had never been reconstituted after Prue's death which meant they would never have met their long lost half-sister Paige. He was disappointed to find that in this other reality, he was trapped in a loveless marriage with Phoebe, who only remained his wife to protect Piper from being killed. By altering reality in this way, Cole resumed his former identity of Belthazor, making him vulnerable to being vanquished. Because Paige also crossed realities, she was able to unite with her sisters to Vanquish Cole once and for all and reversed the effects of his reality warp. Phoebe performed the vanquish herself: after Paige regained her powers and used telekinetic orbing to retrieve the vanquishing potion, Phoebe took it from her and used it to vanquish Cole herself. Cole was so sure of her love for him that he didn't try to escape. Cole is currently trapped in a Cosmic Void, watching over Phoebe. He managed to bring Phoebe together with Drake, who was to restore her faith in love. When Drake later admits he truly fell in love with her, Cole said that was understandable. He also helped bringing Piper and Leo back together. While Phoebe no longer loves Cole, she still has a bond with him. She could feel Cole's presence, but because he was invisible to her, she ignored it. Cole revealed to Drake that he is satisfied with his fate as long as Phoebe doesn't share it.

Coop
In late season 8, the Elders send a Cupid named Coop to help Phoebe's shattered heart and to find her a new love. Phoebe eventually falls in love with Coop and vice versa. It was revealed in the series finale, Forever Charmed, that the Elders sent Coop to Phoebe, because they were hoping that she would fall in love with him to make up for a little of what she had lost through the years. Although it is "against the rules" for a Cupid to find love, the Elders lifted this restriction for Phoebe, as they did for Piper and Leo. Forever Charmed shows that in the future, Coop and Phoebe are married by the Angel of Destiny in Magic School and that they will have three beautiful daughters.