The Reeve, the narrator of "The Reeve's Tale," is able to get into just about everyone's head, an ability he uses to great effect at key moments in the tale. When Aleyn and John announce their intention to watch the corn being ground, for example, we are privy to Symkyn's thoughts. We're told that the miller is aware that the clerks are trying to prevent him from cheating them, and privately promises to get the better of them anyway. This cues us in to be on the lookout for what Symkyn will do to trick them.
After Symkyn has released their horse, however, the narrator's focus shifts to the reaction of John and Aleyn – their frustration at having been cheated and, finally, their plan to get "esement" (payback) by having sex with Symkyn's daughter and wife.
Finally, we are given access to Symkyn's wife's thought process as she joins in the fray the next morning – how, mistaking her husband's bald head for a clerk's white "volupeer" (cap), she clocks him on the noggin by mistake. This last moment of narrative omniscience adds to the comedy of the tale by making fun of the miller's baldness. Throughout the tale, then, the narrator uses his omniscience to create both suspense and comedy.