It takes Dean a while to calm down, but after a few hours, he finally decides to search for Sam. He'll start off with an apology, but he really just wants to talk his brother out of this. Lucifer isn't good for him. He's not good for anyone. Dean wants to make sure his brother knows what he's getting into, and get him out of it.
He checks Sam's room first, but there's no answer when he knocks, and a slight peek in the room didn't reveal anyone in there, so he soon finds himself back at square one. He walks around the bunker for a while, and just as he's about to give up, he hears Sam's voice, and follows it to the library.
Oblivious to his presence, Sam and Lucifer are sitting on the library floor, the latter resting his head on the angel's shoulder. Lucifer is rolling the tennis ball around the floor telekinetically, watching K9 chase after it.
"If I asked where you were last night, is there even a small chance you'd answer seriously?" Sam asks, the first person to speak since they sat down together hours ago.
"In here," Lucifer replies. "Working on K9."
"Alone? Did those three minutes of social interaction wear you out?" Sam asks, almost teasingly, but it's a halfhearted effort.
"Those thirty seconds of Jack wore me out," Lucifer says. "And I wasn't alone. I told Jack to go away and then he stood in the doorway for a few hours."
"Which is basically alone," Sam adds. "You could've come see me. I was waiting for you."
"I know. I just... Jack is nothing like I hoped he'd be, and I didn't like that, and I still don't like that, and I didn't want to take it out on you."
"You could've talked to me about it," Sam tells him.
"There was nothing to say."
They lapse into silence again, both watching K9 run around tirelessly until Sam finally brings up the one thing they've both been avoiding.
"I told you it was going to be a choice between you and him."
Lucifer doesn't have to ask what he means by "him." The scene Dean made makes that pretty clear.
"And I told you, keeping this from him was already not choosing him."
"I could've chosen him, you know," Sam says. "There was no guarantee I was ever going to talk to you again."
"I thought that was what was going to happen," Lucifer admits.
"And you were okay with that?"
Lucifer doesn't answer at first, finally saying, "If I had to choose between not being in your life or just pretending I'm not, I would pick the first one every time."
It's quiet again, not because there's nothing to talk about, but because there's too much, and neither of them are sure where to begin.
Finally, Sam asks, "Did you have to make it so difficult?"
He automatically knows Sam's talking about the continuous jabs at Dean while Sam was trying to find some sort of common ground, which he knew was a bad idea at the time, but he couldn't help it.
"No, probably not," Lucifer admits, but he says it almost indifferently, which Sam obviously doesn't appreciate, so he adds, "I'm sorry. The guy just gets on my nerves."
"That doesn't mean you had to harass him."
Lucifer sighs. "Would it make you happy if I tried to play nice?"
"Are you capable of being nice?"
"Probably not," Lucifer admits. "But I can try, for your sake."
"Can you do me one better and just not talk to him at all?" Sam asks.
"I would be thrilled," Lucifer replies.
They lapse into silence yet again. Lucifer rolls the ball back to him with his mind, K9 following just behind it, and offers it to Sam. The boy takes it and tosses it across the room. Immediately, K9 runs after it, taking it back to them. Sam just gives him the ball the second time, and K9 lies down on the floor next to them and chews on it.
"Dean's probably right, you know," Lucifer says. "This can't be a healthy relationship."
"I know."
"It's probably not going to end well," Lucifer adds, "knowing my track record."
"I know."
"The world has a habit of taking the people I love away from me," Lucifer continues.
"I know."
Lucifer is mildly surprised that Sam accepted that so easily. He didn't try to lie and say that nothing would ever happen to them. He didn't try to say that this was the best scenario there is. He's just being realistic. They both are.
"Gabriel tried to tell me the same thing," Sam says.
"When was that?"
"Earlier today," Sam replies. "And then Dean said it a few minutes later, and here we are, having the exact same conversation."
"It's almost like a sign from the universe," Lucifer remarks.
"Yeah."
"Are you gonna listen to it?" Lucifer asks.
"Do I ever listen to what the universe wants?" Sam counters.
Lucifer smiles slightly at that. "No, I guess not." After a brief pause, he says, "I didn't realize you and Gabriel were still talking to each other." Sam had mentioned before how awkward things were when he didn't feel like he could talk to Gabriel, but he was trapped in the same conversation with him.
"I didn't, either," Sam says. "Apparently, we were both wrong."
"And you two were talking about us?"
"Mm hmm," Sam replies. "It was pretty much what you'd expect anyone to say about us. It's not gonna end well, I should get out now, blah blah blah."
"Fair points," Lucifer adds.
"Not ones I particularly care about, though," Sam says. "And he said he wouldn't tell Dean about us, which didn't work out well."
"'Course not," Lucifer says. "He kills people for sport. You really think you can take his word for anything?"
"You kill people for sport, too," Sam reminds him.
"Exactly, so I know what I'm talking about."
Sam gives him a small laugh, more a heavy exhale than anything else. "I can't believe this is an actual conversation I'm having right now."
"I can't believe this is a conversation I've never had before," Lucifer says.
"I don't even want to think about the weird conversations you've had in your time."
"No, you really don't," he agrees.
Sam lets out a long, content sigh and pulls his feet to his chest, snuggling closer to Lucifer, who rests his head on top of the other boy's.
"If you told me ten years ago that I would be in the library of an overly fancy exclusive hunters' book club talking about my problems to literal Satan, I would've called you crazy — and it takes a lot for me to think someone's crazy."
"If you told me ten years ago that I was going to be spending my nights with a hunter, I — well, actually, I'd probably hope that was true just because it would mean I was out of hell, and honestly, this isn't much less predictable than anything else than has happened since I met you."
Sam chuckles. "Yeah, guess that makes sense."
K9 stands up and drops the tennis ball and walks towards the doorway. Sam and Lucifer share a confused look. K9 never leaves his ball; not since Lucifer rebuilt him as so much more of a dog than before.
"Hey, K9!" Lucifer snaps his fingers, trying to get the dog's attention. K9 glances back, but continues walking away.
"Come here, K9," Sam coos. "There's nothing over there."
"But there is!" K9 says, staring out at the hallway.
"What? What is it?" Sam asks.
When K9 doesn't respond, Lucifer sighs and stands up, much to Sam's disappointment. "Hey, K9, what's up?" He walks over to the doorway with the robot, but there's nothing out there. "What'd you see, boy?"
"I'm not a boy," K9 says.
Lucifer rolls his eyes. "What did you see, 'nonbinary member of society'?"
K9 looks out into the hallway one more time, then walks back towards Sam as he says, "Nothing."
Sam looks over at the angel and asks, "Can he lie?"
Lucifer just shrugs. "Beats me. Probably. Doesn't matter, though. There really is nothing out there."
Sam hesitates, reluctant to believe that, but he decides to roll with it. "Alright, well, come here. I need someone to complain to."
Lucifer chuckles. "I need someone to entertain me, so that works." He teleports to Sam's side, and the light breeze from his wings blows Sam's hair back slightly. "And let the complaining commence."