"Just My Imagination" begins in the bedroom of a little girl having tea with her imaginary friend, Sparkles… a man/unicorn… Manicorn if you will. When the girl is called away to dinner, Sparkles happily tells her to run along, he’ll clean up the tea party while she’s at dinner. Once done, Sparkles is relaxing reading a book when someone enters the room and stabs him to death. When the girls returns, she screams at the sight of her beloved friend and the bloodied bedroom. None of which her parents can see.
Cut to the bunker where Sam wakes up and stumbles into the kitchen to find a table full of treats and his old imaginary friend, Sully, from when he was nine. Sam isn’t sure what to make of him, and before he can decide, Dean comes in. Dean can’t see Sully at first, until, in order to prove he is indeed real, he reveals himself to Dean as well. From there, Sully explains he’s not actually imaginary at all, but is is actually a Zana, a mythical creature that helps give children guidance. Sully then explains about poor Sparkles' murder and asks them to help him find out what happened.
They visit the girl’s house, where she won’t set foot in her room due to the sparkly bloodies gore-fest that it is now covered in, along with Sparkles' dead body. Sam asks, “His blood is glittery?” To which Sully responds, “Even when he’s dead, Sparkles can’t stop shining.” Sully enable Sam and Dean the ability to see the scene. The mom, who cannot see any of it, comes in and ends up unknowingly covered in Sparkle blood.
It’s at this point we flashback to a nine-year-old Sam on the phone with Dean. Dean is breaking the news that dad has said Sam is too young to start hunting with them and for him to remain at the hotel for a few more days. Sully is not only there to comfort Sam, but also reminds him that he is not Dean nor his dad. “You’re Sam. Sam is so awesome.” Sully tells Sam that he doesn’t have to be a hunter and that it’s his choice.
Meanwhile another Zana, a mermaid, is stabbed just as Sparkles was (except, she was in the pool, of course). Sam, Dean, and Sully show up on the scene. Sully is perplexed when asked if there is anyone out to get the Zana. They decide to go visit Weems, another Zana and the mermaid’s boyfriend, to see if he knows anything. Before they can pay him a visit, Weems, a Joe Dirt- looking Zana, is stabbed by the culprit. As he collapses on the ground, he sees that his attacker is a woman in a hood who drives off in a VW Bug. Sully and the boys arrive just in time. Weems is okay and tells them what he saw. They break the news that his mermaid is gone.
Sam and Weems are left alone for a moment and Weems connects who exactly Sam is. According to Weems, Sam broke Sully’s heart. Sam flashes back to the day he left Sully behind, after he gets the call from his dad to finally join the family business. Sully suggests that Sam might want to pursue a different path to which Sam responds, “ I’m a Winchester, I hunt monsters.” Sully begs Sam to find another way, another path. But Sam tells him he is just a pretend friend, not real, and that he doesn’t need him anymore. Sully and Sam part ways.
After the flashback, Sam confronts Sully and tells him how awful he feels about how they left off. Sully says Sam did good. He saved the world. Sam open up about bringing about the darkness, which Sully knows about, and promises he is going to fix it. He confesses that he suspects God wants to help fix it by having Sam go back to the cage. Sully asks if Sam ever thinks about running away anymore. “Not anymore,” he says. Just then he gets a text from Dean saying he found the killer and to meet and to bring Sully.
Of course, it’s a trap! We then see the young woman has tied Dean up and used his phone to lure Sam and Sully in. When Sully sees the young woman, Reese, the story unfolds-- during a game of tag with Sully, Reese’s twin sister had been hit by a car. Sully felt so guilty that he left the field and never took care of another kid. Reese admits that Sully abandoning her when she needed him most made her angrier than him being responsible for her sister’s death. Sully offers himself up to her; if killing him will help her, he wants her do it. Dean breaks free and explains that revenge won’t work, that he has seen real monsters, but Sully and his friends are not. Dean says that when he wasn’t there for his brother, Sully was. Reese drops her knife and hugs Sully.
Sam and Sully exchange goodbyes and Sully reminds Sam that heroes are sometimes scared, but usually it's because the thing they’re going to do is super important. And no one else has the balls to do it. He's clearly referring to the cage.
Sam and Dean say goodbye and take off. In the car, Sam tells Dean it's time to talk about the cage. Dean says no, there’s another way. Sam says “Fine. Then what’s the other way?”
The episode was fabulous in its flashbacks, tapping back into a storytelling tool that has worked so well in previous seasons. The support Sam so desperately needed came from Sully and I love the idea we are returning to the cage.
Which brings me to the best part of the entire episode; scenes from next week’s winter finale, which showed the return of LUCIFER. Hold onto your hats, kids, it’s going to be a long winter hellatus!