Demonology - S4-E17
Other mistake: Prentiss pulls up to a bar and the shot shows her looking out of the car window. "BAR" is shown reflected in red on the car window, but it is readable from left to right under the closeup of Prentiss's face when we see her. The reflection of "BAR" should have been backwards since it's a reflection of the sign on the building.
Answer: "The Boogeyman", s02e06. Spoiler alert: The kid is Jeffrey Charles and at that point he had already killed 3 other kids. Jefferey basically hated and resented other kids after his mother abandoned him and his father spent a lot of time with other children because of his job. Jeffery would lure kids Into the Woods and then beat them to death with his bat just because of hate, no particular "reason." The scene you're describing, Jefferey agrees to walk Tracy home when her "buddy" leaves her (at this point the FBI announced there's a serial killer on the loose and kids should walk with a buddy). Jeffrey gets mad at Tracy for walking too slow and for complaining, and he takes a swing at her, causing her to flee Into the Woods and have Jeffery chase her.
Bishop73