“Reservation Dogs.” Season 3’s trailer may mark the end of an era for Sterlin Harjo and Taika Waititi’s dry comedy, but based on the video, this last season also marks the start of something new for its central characters.Since its premiere in 2021, “Reservation Dogs” has always been about the liminal space between childhood and adulthood. The series started with Bear (D’Pharaoh Woon-A-Tai) forgoing his friends’ plan to ditch the reservation after his persistent Spirit (Dallas Goldtooth) persuaded him to improve his home rather than abandon it.