<sod>Other plot devices are simply intended to get the protagonist to the next scene of the story. The enemy spy, who suddenly appears, defects, reveals the location of the secret headquarters, and is never heard of again, would be an extreme example. Without this 'device' the hero would never find the headquarters and be unable to reach the climactic scene; however the character becomes less of a plot device if the author gives them a back-story and a plausible motivation for defecting and makes them an interesting character in their own right.<eod>
<sod>Other plot devices are simply intended to get the protagonist to the next scene of the story. The enemy spy who suddenly appears, defects, reveals the location of the secret headquarters, and is never heard of again would be an extreme example. Without this device, the hero would never find the headquarters and be unable to reach the climactic scene; however the character becomes less of a plot device if the author gives them a back-story and a plausible motivation for defecting and makes them an interesting character in their own right.<eod>