Prepare to take a glimpse of Sam Winchester's (Jared Padalecki) childhood in the next episode of "Supernatural" season 11.

The trailer for the episode that will air on Dec. 2 titled "Just My Imagination" reveals that Sam will be shocked after his imaginary childhood friend Sully (guest star Nate Torrence) reappears. He even throws a punch when the make-believe creature suddenly turns up behind him. But Sam will be more shocked to know that his older brother Dean (Jensen Ackles) can also see Sully this time.

But Dean does not seem to enjoy the reunion, thinking that having imaginary friends is a dumb idea.

Based on the synopsis of the episode, Sully will ask the Winchesters to find the one responsible for the gruesome murders of a slew of imaginary friends that were created by children. In one of the scenes in the trailer, Sully and the Winchesters are standing in front of a murdered mermaid, which Sully describes as "a blood bath."

Can the Winchesters catch the killer before all the kids' imaginary friends all turn up dead?

Meanwhile, Padalecki reveals that the Winchesters will spend more bonding moments together in the upcoming episodes of "Supernatural" season 11.

In a spoiler on Entertainment Weekly, the actor shared information about Sam and Dean's relationship in "Supernatural" season 11.

"It's such a massive big bad that they've let loose that a lot of what's going on this season [is] the brothers side-by-side working in parallel righting this wrong," Padalecki explained in the trailer. "We're doing some cool stuff this season where the brothers [are] even starting to right past wrongs with each other. They're starting to remind each other that they care about each other, that they're there for each other and sorry about what happened."

"Supernatural" season 11 airs Wednesdays on The CW.