The spell calls for a few lines of Enochian chanting.
The logical thing in this situation is to call Cas, see if he's up for doing it. It's his language, and he's the one least likely to fuck it up. Dean's out, because even with the words written out phonetically, he can't get them to sound quite right. Sam...
"I'll do it," he says, just as Dean is about to pass off the role to Castiel. They both glance at him, Dean with a raised eyebrow and Cas's brow furrowing. Sam's read and reread the lines over a dozen times now. He can practically feel the words vibrating from where he's keeping them under his tongue. Dean shrugs.
"Hey, let Sam show off his nerd brain," he tells Cas. Castiel's brow furrows even more, if that's possible.
"Are you sure you know the pronunciation, Sam?" Sam nods. Pronunciation? That was the first lesson, the very basics. Sam could hold a conversation. Sam could recite entire prayers and verses in Enochian. Sam knows the language like he was born speaking it, and sometimes he still talks to himself in it. It brings him back to before.
("Are you sure this is how it sounds?" Sam asked in English. Lucifer looked annoyed.
"Yes, Sam, I'm sure."
"It's just..." Sam licked his lips, turning the words over in his mind, the way they had rolled so easily off of Lucifer's tongue. "I think I learned some Enochian topside. It didn't sound like this."
"Do you really think any human understands our language better than I could? None of you heard it for centuries." He smiles at Sam, sweet, almost indulgent. "Except for you, now. Don't you feel special." It's only teasing, but Sam focuses, gets his words in order.
"Yes, I do." He speaks the Enochian the way Lucifer taught him this time. (Because of course, the first thing Lucifer ever taught him to say was yes, even if that can't mean what it once did anymore.) It doesn't sound anything like the books he once read said it would, but it sounds right in his mouth the same way it does in Lucifer's. Lucifer's smile widens.
"Oh, Sam." He sounds delighted. Sam finds himself smiling back.)
"I'm sure." A few hundred, or a thousand years, or an eternity later, because time never really worked in Hell, and Sam forgets more words in English now than he ever does in Enochian. He can even see where whoever translated this spell did it wrong, and he's already fixing the Enochian in his own head, replacing a few words and changing the sentence structure. He's not sure how Cas didn't catch it, but maybe it wasn't incorrect enough to matter. It matters to Sam.
They go through the motions of setting up the spell, and all the while, those words are buzzing in Sam's head. It's the opportunity of it that excites him, a chance to speak aloud a language he's confined to his own whispers, a chance to show that Lucifer's lessons were still useful, could still help Sam even when he wasn't there to talk to anymore. Sam's thought about asking Castiel to converse with him in Enochian before, briefly. That would invite too many questions, how Sam knows the language beyond spellwork, when he learned, who taught him, and then he'd be staring down the barrel of pity or distrust again. He's not sure which is worse at this point.
This is an acceptable middle ground. Castiel and Dean won't question him knowing this. He can say the words out loud, feel the thrum of them in his throat again. Sam wants to hear himself say them. He wants to close his eyes and hear the words echo and pretend, for a moment, that someone will speak back.
("Tell me something," Sam said. Lucifer was rearranging a sky that did not really exist above them. He was frowning as the stars darted and flickered in and out. Sam couldn't tell how close he was getting to the real night sky, but some of it must have been off or Lucifer wouldn't look so tense. Sam leaned back further into Lucifer, and Lucifer looked at him. The frustration melted away.
"Like what?" His hand came up to stroke Sam's hair. Sam remembered being scared the first time Lucifer touched him here, not just because it was Lucifer, although, yes, but because it had felt like no physical touch he'd ever experienced. Sam could remember freaking out, but he couldn't recall what he compared this against, what being touched felt like when you were only flesh and bone and not soul and grace.
"Anything. For practice. I want to see if I can understand it without context." Lucifer tilted his head. His eyes were nothing like the stars twinkling far away above them. They were closer to supernovas, a never-ending explosion at the core of him, terrifying and glorious.
"The language of angels was made for your tongue," Lucifer said. "My siblings never made it sound so perfect." Sam swallowed.
"I was thinking more of a fun fact or something." Lucifer leaned down to kiss his forehead.
"That is a fact.")
"Ready?" Dean asks. Sam and Cas both nod. Sam can feel his heart beating faster. A few more seconds. For a moment, he can almost hear Lucifer's voice, and he worries he's hallucinating again.
("Sam." Lucifer was perched on his bed. Lucifer was still in the Cage. "Talk to me. You'll forget how otherwise." Sam glanced towards the motel bathroom. Dean's shower was loud enough that he wasn't too worried about being heard, as long as he kept his voice low.
"And if I make a mistake, you're not going to be able to correct me," Sam pointed out, "because you are me." His hallucination inclined his head, accepting the rebuttal. There was a subtle wrongness in the way he moved. Every time Sam saw this version of Lucifer, the gap between him and the real thing grew wider, but Sam couldn't bring himself to shut this out yet, not when it was all he had, a walking talking memory.
"Do it anyway. It'll make you feel better." Sam's chest ached. It needed to remind him every now and then that there was a hole there that would never be filled back up. That Lucifer was right, and they were the missing pieces of each other, and the moment the puzzle came together, the universe came along and pulled Sam's piece back out.
"What do I even talk about?"
"Whatever you want. Tell me about your day." Sam snorted humorlessly.
"You weren't there. It sucked. Same song-"
"Different verse," Lucifer finished. Sam knew he goaded the hallucination into it on purpose, if that was even something you could do with a figment of your imagination, but it was just close enough to something the real Lucifer said to ease the hurt a little. Sam bent down to get a change of clothes out of his bag. "I miss you," Lucifer said, quietly.
"I-" Sam responded.
"What did you say?" Dean interrupted. Sam hadn't heard his shower end. He shut his mouth. Lucifer was gone.
"Nothing." It took him a moment too long to translate Dean's words, find the right response in English. The look Dean was giving him let Sam know exactly how little he believed him.
"Sam, you know you can talk to me..." Dean pushed. Sam straightened, holding his clothing close to his chest.
"You better not have used all the hot water," he said and fled the scene.)
Sam runs a hand through his hair. Dean gives him the go signal.
He opens his mouth, and the words spill out, and they're perfect and right and he missed them-
He speaks for about twelve seconds before Cas shouts at him to stop, and he falters in surprise. Cas looks horrified, as though Sam has been slaughtering babies with his bare hands and not simply talking.
"Cas, what's wrong?" Dean asks, reaching out to put a hand on the angel's shoulder. Cas startles badly, eyes still locked on Sam. Sam feels himself shrink back from that gaze.
"Where," Castiel demands, and though his voice is hard as iron, his face is a cascade of expressions, all of them ruled by a combination of horror and confusion, "did you learn that?" Sam can't breathe.
"From-" He struggles for something, for the right word, and it's there in Enochian, from another hunter, from a book, anywhere but from Lucifer himself, but he can't translate any of those thoughts into English fast enough.
"So he mispronounced a few things, Cas, calm down. We'll start over, and you can say the magic words this time." Cas shakes his head.
"No. This wasn't a mispronunciation. It was far too consistent. And... archaic." Cas almost sounds angry when he continues. "Who taught you this? It's wrong." He spits the word out.
"I don't understand," Sam says.
"The way you speak hurts. Enochian is harmonious, it's... beautiful. I can barely stand to hear what you're saying, Sam." Dean is giving Sam a weird look now. Sam can't see a way out of this.
"I can explain."
"It feels... defiled. I'm not even sure how someone could twist our language like that." Cas continues.
"Lucifer," Sam says, "he taught me." Dean's mouth twists angrily. Cas looks... less so.
"So, what, that son of a bitch shoved a cursed version of Enochian in Sam's head?" It's not cursed or defiled, Sam wants to protest, it was his, it's ours, it's the only part of him left in me. He doesn't say any of that. Castiel and Dean don't know what happened in the Cage. They know Sam came back with damage, a fuckton of damage, and they'd assumed Lucifer was a part of it, if not the sole cause. Sam's pretty sure any attempt to defend Lucifer at this point will lead to accusations of Stockholm Syndrome or worse, so he's keeping quiet.
Castiel is watching him. He still looks shaken, but there's something else there. Something sad.
"No, Dean," he says. He takes a deep breath. "Sam, Lucifer was alone for a very long time."
"So?" Sam knows. Sam was there. Sam was the reason he wasn't alone anymore, until Dean and Cas tore them apart.
"What you're speaking is not Enochian." Cas sounds like he's trying for gentle and missing by a mile. "Not anymore."
("Thank you," Lucifer said as he trailed a hand down Sam's bare chest, a tease that may or may not lead to sex.
"For what?" Sam reached down to take his hand and brought it to his mouth, kissing along Lucifer's fingers and palm and wrist. Lucifer watched him, pleased.
"Many things," he murmured, "but right now, for talking with me." He stroked Sam's cheek, back down his neck and his chest again, fingers tracing the tattoo that had done nothing at all to ever keep him out. "It's one of the last connections I have to them." He looked so tired, Sam realized. "They cast me out, Sam. Michael destroyed my wings beyond any hope of healing. They condemned me to silence outside of the revelations of the Host. But they could not make me forget my own tongue." Sam reached up, pulled Lucifer closer, and the angel came without much protest, laying in Sam's arms. "I spoke it to myself for centuries, and now, here you are, willing to learn and converse with me."
"Of course I would. I love you," Sam said before kissing him. Lucifer sighed happily.
"Beautiful," he said.)
