With Jo taking all Lucifer's attention, there's no one for Jack to run into when he leaves Gabriel and Sam to have some quality time.
He expects to be all alone until Gabriel and Lucifer are ready to find him again, so he goes straight to where he would have gone had this been his universe — his room. He pushes the door open, and to say he's surprised to see clothes already in there would be an understatement. They're not his clothes, either. It's a woman's room, though there are too many women in the bunker for him to guess whose it is.
Jack just stands there for a few moments, dumbfounded. Someone else is living in his room. It makes sense, obviously. He doesn't live here. This isn't his universe, so it's not his room. It's just exactly where his room should be, had he been home.
Home.
He misses it. He misses it more than he can put into words. He misses his room. He misses his friends. He misses his hunts. He misses his whole universe.
"Jack?"
Jack immediately shuts the door, as if he was doing something wrong. He wasn't, though. He just wanted to go to his room. He didn't know it was someone else's room. That doesn't make it wrong, does it? That he was looking in someone else's room?
He turns around to see Castiel looking at him, perplexed. Jack beams at the face in front of him before remembering that this isn't really Castiel. It's what his Castiel could have become, but it's definitely not his Castiel. Jack never got to show him their perfect universe from the womb. That was the foundation of their relationship. The only thing this Castiel knows about him is that he's the son of Satan, which isn't quite the same.
"Hi," Jack says, holding his hand up for a brief wave.
"What are you doing?" Castiel asks cautiously.
"Oh." Jack glances at the door behind him with a frown. "This used to be my room. You know, in my universe."
"You lived here?" Castiel repeats, seeming very surprised by something Jack had just assumed he knew.
"I did," Jack says.
"And you had your own room," Castiel adds.
Jack nods. "Yes. I do sleep, and I wasn't going to sleep on the floor."
"You weren't in the dungeon?" Castiel ventures.
"I've been to the dungeon," Jack says, confused. "I didn't live in it, though." He cocks his head to the side, squinting slightly. "You still think I'm the bad guy, don't you?"
"Of course not," Castiel says, but Jack can sense that he's lying.
"We were friends," Jack tells him. "You and me and Sam... I don't think Dean liked me, though." He pauses, then adds, "That's one thing that didn't change between worlds."
"Why would we help the son of Satan?" Castiel asks.
"Because I asked you to," Jack says. "Before I was born. And you believed in me, and then..." And then Lucifer killed you. "And Sam and Dean trusted you."
"You spoke to me before you were born?" Castiel repeats, confused. "How?"
"It's hard to explain," Jack says. "I don't have very good control over my powers, but somehow I managed to..."
Jack reaches for Castiel's hand, and the angel immediately pulls it away.
"What are you doing?" Castiel asks, obviously on edge.
"Trust me," Jack says. "Please."
Castiel eyes him warily, then slowly puts his hand out. Jack takes it in his own and closes his eyes. He can summon the image with ease — a look at a perfect world, at the world he wanted to make; that he still wants to make. But how does he show it to Castiel? He was barely a fetus at the time. He has no idea how he did it.
But then Castiel gasps, and Jack opens his eyes just in time to see the yellow fade from Castiel's irises. He remembers that happening the first time, way back when. He saw it through his mother's eyes. Does that mean it worked?
Castiel looks at him in wonder. "What was that?"
"Me."
"You..." Castiel gapes at him. "I think I understand it now."
"I'm glad," Jack says. "No one else does. I mean, Gabriel and Lucifer are trying to understand, but I don't think they do. Not the way you used to."
"Gabriel and Lucifer?" Castiel repeats. "You've been with both of them this whole time?"
"Well, not the whole time," Jack says. "It was just me and Gabriel at first. He seemed as lost and confused as I was."
"I knew you were with Gabriel," he says. "Gabriel was the one who told us you were missing a few days ago. I didn't know about Lucifer, though." He seems concerned, though Jack doesn't understand why. "What have they been telling you?"
"Oh, they're trying to teach me to use my powers," Jack says. "I'm working on telekinesis. See?" Jack steps away from the door so Castiel can see when he opens it with his mind. "I'm getting really good at it."
"Why are they teaching you this?" Castiel asks warily.
"They think I can break the warding in the bunker so we can all leave," Jack says, unable to hide the pride he feels. They really think he has that much potential — that he has the potential to overpower God Himself.
"Really?" Castiel asks, but then answers his own question, presumably talking aloud to himself. "You might be able to. You're definitely powerful. A different type of powerful from Chuck, but powerful nonetheless..."
"Lucifer and Gabriel think I can do it," Jack says. "Won't that be awesome? We'll finally be free!" Maybe Chuck will finally send him home once his little experiment is over. As much as he likes Gabriel and this world's Lucifer, he misses Sam and Dean too much to even think about staying here.
"It would be interesting," Castiel says. "I don't know how Chuck would feel about it, though."
Jack frowns. He thought Castiel would be more excited. Isn't this what they want? Doesn't everyone just want to get out of here?
"I'm going to go back to the war room and tell the Winchesters that I found you," Castiel says finally. "Would you like to come with me?"
Jack beams. "I would love to go with you!"