This is a sequel to Lights but can be read on its own.
A/N: *sighs* So, I don't think I should have to do this, but I'm irritated so I'll bite. Someone left a very ignorant comment - which I've since deleted - telling me to put up a "gay warning" (which is quite derogatory imo), so consider this it: on this website, if two characters are listed within square brackets, this means they are a PAIRING, which implies romantic involvement. That is your "warning". If that pairing is not for you, don't read it.
There is no smut in this fic.
Sam's eyes crack open in the darkness of his room. The bunker is quiet and still, and yet his heart rate is elevated. His fingers curl around the knife hidden under his pillow.
There's someone here.
He turns his head to the side slightly, scanning the room, and his eyes land on a dark figure at the foot of his bed.
Instead of leaping up to defend himself, he lets go of the knife, sits up and wipes a hand over his face. "Dammit Luci, you gotta stop doing that."
His eyes have adjusted to the darkness now, and he can make out Lucifer's familiar features as he moves to sit cross-legged on the foot of the bed, facing Sam. "Would you rather I showed up in the middle of the day, when you're with Dean?" He raises an eyebrow. "I can almost hear the gunshots."
Sam slumps back against the headboard, muttering "Wish you never showed up at all," under his breath, but he doesn't mean it. Lucifer grins like he knows. "I need to sleep, Lucifer. We're working in overdrive right now."
Lucifer sobers, fixing Sam with a piercing stare. "The trials."
"Yeah, Kevin's translated enough that we can get started –"
"Don't."
Sam blinks. "What? Why?"
"You'll die," Lucifer says simply. When Sam doesn't say anything, he goes on, "There's a reason no one's managed it before, Sam. They're lethal, and they only get worse. Most die from the exertion of the first, never mind the second." He pauses, and surveys Sam thoughtfully. "I don't doubt that you are strong enough to make it past the first two, Sam. But complete the third and you'll die. It's a certainty."
Sam scowls at his knees. It's with both hands clenched in his blankets that he mutters a quiet, "So?"
Sam doesn't look up, doesn't want to see the pitying look on Lucifer's face as he begins, "Sam –"
"It would still work, wouldn't it?" Sam cuts across. He doesn't wait for an answer. "The rest doesn't matter. If I can actually do some good –"
There's a flurry of wingbeats and suddenly Lucifer is practically in Sam's lap, his knees on either side of Sam's thighs. Sam jerks back in surprise, but there's nowhere for him to go. "And here I thought you were the one angel that got the personal space memo," he mumbles, averting Lucifer's eyes and trying to ignore the way warmth is spreading south in response to a lap full of archangel.
Lucifer delicately cups Sam's jaw with cool fingers and gently tilts Sam's head up to look at him. "Stop that," he says sternly. "Your entire life consists of you trying to do good in the world."
Sam scowls. "Trying," he repeats scornfully. "What use is that, when I screw everything up anyway?"
"You can cut the self-deprecating bullshit right now." Lucifer's calm but deadly tone slices through Sam like icy water and sends shivers down his spine. "People make mistakes. You're not a bad person."
Sam's silent for a moment before looking the angel straight in the eye. "Not like you to excuse human behavior."
"I'd excuse anything for you, Sam," he replies evenly, "but that's not why I'm saying it."
Sam's listening, but it doesn't change the way memories of what he'd do for a taste of demon blood creep up on him during sleepless nights; doesn't change the way Dean tirelessly puts faith in him and Sam continues to fail his expectations; doesn't change the way everyone he's loved has lost their lives because of him; doesn't change the way he started the apocalypse.
Doesn't change the way he threw Lucifer back in the cage like it was nothing to him.
Lucifer's laser-focus stare is still trained on him, and Sam gives him a small smile he knows doesn't reach his eyes. "You don't lie," he says eventually.
"No," Lucifer says, tight smile mirroring Sam's, "I don't."
Silence falls between them. At some point Sam leans forward, rests his head on Lucifer's shoulder and wraps his arms around the angel's waist, because there's no denying being close to him gives Sam a sense of comfort he never thought possible and dammit he's selfish when it comes to Lucifer. He breathes in the familiar smell of something he can't name, like lightning striking ice, and closes his eyes as Lucifer runs his fingers through his hair, wrapping his other arm protectively around Sam and murmuring something in a soothing tone. Sam thinks it might be Enochian.
Eventually Sam pulls himself back with the intention of telling Lucifer he should go so he can get some sleep, but Lucifer speaks first. "Don't do the trials Sam."
Sam's surprised to see pleading in the angel's eyes. "I –" he starts, but Lucifer leans forward quickly and then they're kissing, and Sam freezes because they don't do this, they're not romantic, they have a perfectly platonic relationship; sure, Sam kissed him that one time but that didn't mean anything, and anyway, this isn't right –
But then something clicks and it's so right that Sam kisses back, hungry for the feeling of Lucifer's cold lips on his heated ones. He bites on Lucifer's lower lip and teases it with his teeth, and when the archangel gasps Sam takes the opportunity to slide his tongue against Lucifer's. There's sparks dancing along his skin and stars behind his eyelids and heat spreads through him wherever the archangel's cool touch meets his skin, but it's not just arousal; Sam feels like he's taking a desperate gasp of air after a lifetime spent drowning. It feels like coming alive.
But it's not enough to change his mind.
When they break apart, breathless, Lucifer fixes him with an incessant stare once more. "Don't. Please." Sam doesn't think he's ever seen such sadness in those frosty eyes. "I don't think – I can't be separated from you again. Not now."
Sam's stomach jolts at the raw emotion in the angel's voice. "I won't," he says, and the lie sounds even emptier than it feels, ringing hollow in his ears.
Lucifer hangs his head, because of course he knows Sam is lying – a stranger would have been able to tell, never mind Lucifer who seems to know Sam inside out – but doesn't question it, instead murmuring that he should go.
"Hey wait," Sam says, grabbing Lucifer's wrist before he can go flying off, "uh, why don't you stay? You know, tonight."
Lucifer tilts his head in confusion. "You need sleep. I don't sleep, Sam."
"Pretend?"
Lucifer smiles at the hope in Sam's tone. "I suppose I could."
Sam sleeps sounder and deeper than he has in years that night with an archangel pressed against his back and an arm wrapped tightly around his waist, and in the morning when Dean bursts in to his bedroom wearing his prized 'Kiss the chef' apron and declares that breakfast is ready, Lucifer is nowhere to be seen.