Charmed

 "In the television show ""Charmed,"" Cole Turner, played by Julian McMahon, is a complex character who is both a demon and a love interest for Phoebe Halliwell. Initially introduced in Season 3, he starts as a charming and charismatic character but is later revealed to be the demon Belthazor, who struggles with his dual nature.

Throughout the series, Cole's character experiences significant development. He battles with his love for Phoebe and his demonic instincts, ultimately leading to a tragic arc. In Season 5, after several conflicts and attempts to redeem himself, Cole becomes increasingly consumed by his darker side. In the finale of Season 5, he is vanquished by the Charmed Ones after he is manipulated by the Source of All Evil and attempts to kill Phoebe.
However, in Season 6, he returns in a different form as a ghost and continues to play a role in Phoebe's life, attempting to guide her and help her confront her feelings. His presence remains a significant influence on Phoebe until the series concludes. Cole's character is notable for exploring themes of love, redemption, and the struggle between good and evil throughout the series."