Something Wicked (S01E18)

Sam and Dean investigate a small town in Wisconsin where children are falling into comas for no apparent reason. The brothers discover that a witch is creeping into the bedrooms of the children and stealing their "life force". While battling the witch, Dean recalls a past mistake that almost cost Sam his life at the hands of the very same witch, an event that has fueled Dean's protectiveness over Sam and his blind obedience to his father. (Warner Bros. UK)