Castiel is depicted as a tall, handsome man with short brown hair and blue eyes. He is typically seen wearing a trench coat, a dress shirt, and a tie, and he often wields an angelic blade. Castiel possesses a range of supernatural abilities, including the power to fly, heal wounds, and smite demons with a single touch. He is also able to communicate telepathically with other angels and humans.
Throughout the series, Castiel's relationship with the Winchesters evolves from one of master and servant to one of friendship and mutual respect. He becomes a trusted ally to the brothers, and he frequently provides them with assistance in their battles against demonic forces. Castiel's loyalty is often tested, however, as he is torn between his duties to Heaven and his growing attachment to the Winchesters.
Castiel's character has been praised by fans and critics alike for his complexity and his compelling storyline. He has become one of the most popular characters in the Supernatural universe, and his presence has greatly enriched the show.