Dumain

Dumain was a demon sent by The Triad to turn Christy and Billie Jenkins against the Charmed Ones.

He'd been an "imaginary friend" to the Jenkins' when they were little girls. After Christy was kidnapped by demons, it is presumed that he helped train Christy in the path of evil in the 15 years before Billie rescued her.

In 2006, Dumain approached the Triad with an audacious plan. He proposed to have Christy turn Billie against the Charmed Ones by making Billie think the Charmed Ones were actually evil, or at the very least on the verge of being corrupted by their power, he then expected there to be a huge battle which would kill both sets of sisters and permanently shift the balance of power in favor of the forces of evil. The Triad liked the idea so much that they promised to make Dumain one of them if it ever succeeded.

It is seen in Gone with the Witches that Dumain posesses the power of Conjuration when he conjures Billie's Book of Shadows. He used it to find out the Charmed Ones' weaknesses, and used them to keep the Halliwells occupied long enough to turn the magical community against them.

The Triad wasn't satisfied at fighting the Charmed Ones to a draw, and told Dumain to have the Jenkinses summon the Hollow. Dumain didn't like this idea, fearing that the Hollow would infect the Jenkinses and make them kill the Triad for their powers as well. However, he reluctantly went along.

The Jenkinses faced the Charmed Ones in the manor, and in the resulting battle, Phoebe, Paige and Christy died. Piper went back in time to save her sisters and Dumain urged Billie to do the same with her projection power. However, when he tried to get Billie to go to the Triad first, Billie realized she was being played, and turned back to the side of the Charmed Ones.

Christy managed to find Dumain herself, believing that they needed to get to the Hollow before the Charmed Ones did, Dumain stole Coop's ring. He and Christy then used it to go back in time and warn the Triad. However, Billie projected herself and the Charmed Ones back in time as well. The Charmed Ones vanquished the Triad with potions. Dumain was shocked that the Charmed Ones had been able to track him down. Before he could get away, Piper blew him up. Past Dumain tried to shimmer out of danger, but Piper blew him up in midshimmer, vanquishing him.

Trivia

 * Dumain is the final demon vanquished on the series (not counting flash-forwards).

Appearences
Dumain appeared in a total of 3 episodes throughout the course of the series:


 * Season 8
 * Gone With The Witches
 * Kill Billie: Vol. 2
 * Forever Charmed