Episode 14 of "Angel"
s01e14 I've Got You Under My Skin

Angel accidently calls Wesley 'Doyle' while he is arguing with Cordy, who has just made inedible brownies. We later learn Angel feels pangs of guilt over Doyle's untimely death. Suddenly, Cordelia receives a vision about a young family. When Angel and Wesley visit the residence, they notice a boy sleepwalking in the street. Angel saves the boy, named Ryan, from an oncoming car. When Angel goes inside the house to get cleaned up, Wesley takes a look around and deduces one of the members of the family is possessed by a demon. Meanwhile, to show their undying gratitude for Angel's bravery, the family invites him over for dinner the following evening. Wesley informs Angel about the demon presence and the next day, they create a brownie recipe that will reveal the demon's presence. During desert, Ryan puts on a demon face and Angel brings the family AI to exorcize it. While Cordy stays with the family, Wesley and Angel go to the local church to find the priest to exorcize the demon, but they soon learn from the nun that the priest died six months earlier. Wesley decides he will perform the exorcism and begins the ritual. The strength of the Ethros demon is such that he will most likely kill whomever is performing the exorcism because of its need to inhabit another body, so Cordelia travels into town to purchase a box to contain it. However, the box is too small, and the Ethros demon escapes after its expulsion. Angel and Wesley track him and kill him, but not before learning Ryan was evil before the demon ever entered his soul. They go to the house and rescue Stephanie, Ryan's sister, from a fire he had started. Ryan is taken into police and social services custody, and the family thanks Angel for his work.