From what Supernatural fans have seen of Sam and Dean’s childhood, it was filled with many parent-less nights spent in motels eating microwaveable dinners. So suffice it to say that it’s not surprising to learn that Sam had an imaginary friend growing up. What is surprising is that, in this week’s episode, said imaginary friend is returning … and he needs help.

However, Sam’s imaginary friend, played by Nate Torrence, isn’t the only big return this week: Supernatural fan-favorite Richard Speight Jr. is back to direct what Jared Padalecki and Jensen Ackles describe as another format-bending hour. “Richard Speight has a funny, quirky, you’d-never-see-on-another-television-show kind of episode. That’s gonna be great,” Padalecki tells EW.

Ackles adds: “‘Just My Imagination’ is really fun. I felt like I was on a sketch comedy show doing the show. One week I’m having a fight with two people inside the backseat of a car, and the next week I’m killing ghosts or saving somebody from pending death, and then the next week I’m in a room with an imaginary guy who’s dressed up like Bert and Ernie and we’re just riffing and having these awesome funny dialogue scenes.”

Specifically, the episode introduces Sully, Sam’s imaginary friend, who returns because he’s in danger. “A friend from Sam’s childhood comes back that Dean didn’t know — that he only knew from Sam’s telling him about his friend,” Padalecki says. “But Sam’s childhood friend has friends that are being killed off and he needs Sam’s help and he knows what Sam does.”

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But it sounds like Sully might not be any safer with the Winchesters. “One of my favorite lines of this season so far is during this episode and I’m going to go ahead and give it to ya,” Ackles says. “When Dean walks in and sees Sam talking to nobody and says, ‘What are you doing, who are you talking to,’ [Sam’s] imaginary friend reveals himself to Dean for the first time. And then Sam says, ‘This is my imaginary friend Sully,’ and Dean blank-faced just goes, ‘I’m gonna get my gun.’ That is my favorite line this season so far,” Ackles said.

So while Dean adjusts to having Sam’s friend around, the good news is that Sully’s presence is going to give fans a glimpse into a side of Sam they might not have seen before. “It also provides a glimpse into Sam’s past and into Sam’s childhood and provides a Castiel for Sam almost,” Padalecki said. “Because we get to see a side of Dean when he’s with Cas that we don’t really get to see with Sam because Sam and Cas don’t have the relationship. But Sam and his childhood friend do have that relationship, so we get to see a cool part of Sam and see Sam admit to things that he’s not hiding from his brother but he just wouldn’t burden his brother with. So it’s really cool and I hope [Nate Torrence] comes back.”

Supernatural airs Wednesdays at 9 p.m. ET on The CW.