When the character of Alec was conceived for the series' season 2, the writers knew they wanted him to be a somewhat amoral X5 with a sharp wit. They chose to immediately hire
Jensen Ackles for the role, who had previously played a rogue serial killing X5 in a season 1 episode. They explained the actor's return in a different role by saying that Alec was his former, and deceased, character's twin. Although they had only seen Ackles as a dramatic actor in his previous roles, everyone in the production was pleased to see that Ackles had a natural talent as a comedian.
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