The Dark Defender is a comic book character based on the Bay Harbor Butcher, seen in Season Two. Dexter comments that the amount of leather he is seen wearing would be uncomfortable due to the heat of Miami.
When Dexter is at one of his Narcotics Anonymous meetings, he falls asleep while someone else is speaking. He dreams of the day his mother was murdered, though it is notably different that what actually happened. Laura Moser is not covered in blood, there are no other dead bodies, nor is there any blood in the container, and Brian Moser is nowhere to be found.
Before the men can kill Laura, the door to the container opens, revealing the Dark Defender, who then kills all three of the men with relative ease. The Dark Defender removes his hood, revealing himself to be Dexter. The younger version of Dexter has disappeared from Laura's arms, causing her to realize that the person who had just saved her life was her son. Dexter then tells her that she is safe, and helps her up. Clapping is then heard, and Dexter awakens from his dream.