The first time Carlos notices it, they're in bed, enjoying a Saturday night in. Cecil lies back, a satisfied sigh falling from his lips, and Carlos lays his head on Cecil's chest, fingers intertwining over his stomach. He's lying on Cecil's left side, and he settles, snuggles closer, expecting to hear that faint rhythm, but –

Nothing. Carlos frowns and listens harder, pressing his ear more fully against Cecil's chest. "What are you doing?" Cecil asks, laughing a little and moving his head to peer down at him.

Carlos lifts his head, and another investigation in a weird aspect of Night Vale seems downright unnecessary when Cecil is this close, flushed and sweaty and smiling at him like that. "Nothing," he replies belatedly, and leans up to feel that smile against his own lips.

But the thought doesn't go away, because Carlos is a Scientist, and solving things are what Scientists do. He finds himself writing hypotheses in his head, brainstorming causes and consequences for Cecil's lack of a heart-beat whenever there's an idle moment in the lab. What could it mean? Where is it located, if not in Cecil's chest? Or is it simply … Carlos feels like a moron, but is it simply quiet? Is that another inexplicable Night Vale quirk? The biological repercussions alone keep Carlos up at night.

And what then, if Cecil's heart is somewhere else? Is he not human? There's certainly something off, something unnerving about him already, something that makes him fuzzy at the edges whenever viewed in Carlos's peripheral vision. But it has to exist somewhere, Carlos is certain. Cecil can't be heartless – not even in the strictest, most literal sense. In many ways, Cecil is the heart of Night Vale, and a man who coos at virtual kittens like Cecil does, looks at Carlos with the amazing, somewhat terrifying love that Cecil does, can never be defined as heartless. No, it has to be someplace else, like in those science-fiction shows Carlos loved as a child.

He spends another night at Cecil's, because his room above the lab doesn't allow them much privacy, and it still smells faintly of frog – at least, what Carlos hopes is frog. Cecil cooks, wearing that completely unnecessary glow-in-the-dark apron he loves, and Carlos stands behind him, pressing his hands experimentally to Cecil's stomach and sighing internally in annoyance when he doesn't feel anything. He noses at the nape of Cecil's neck and suggests, "A massage after dinner? For you. I mean -"

Cecil turns to look at him, shushing him with a glance. It's a little mortifying, how difficult it is for him to say stuff like that, but Cecil usually puts him out of his misery soon enough. Like he's doing right now, looking surprised, but pleased. "Perfect Carlos," he says, his acquiescence, and gives Carlos a small kiss. "Now get out of here, you're distracting the chef – I don't want to cut off a finger again, this is my mother's recipe."

"Again?" Carlos asks, but walks into the living room before he can get a reply.

Dinner is good, and the massage and the resulting sex is even better – but Carlos, despite spending over an hour with his hands all over Cecil, is no closer to an answer, and his frustration is almost palpable.

He tells himself to give it a rest. Repeatedly. But it's just not in his nature – Carlos was incessantly curious before his chosen profession made it socially acceptable, and Cecil is a puzzle he wants to spend years unraveling. Carlos is incapable of letting any aspect of his heart-shaped conundrum go.

It's clear, however, that the scientific method has let him down. It's far from the first time since his arrival in Night Vale, and – although terribly disappointing – this is usually easier to deal with when he has Cecil to ask about all the mysteries of the town. But to flat-out ask him about this seems overly rude – Carlos isn't the most suave of people, but even he is pretty sure no one should ever ask their significant other where their heart is. And it's definitely too embarrassing to ask any of his coworkers about – he doesn't think they'd have much to bring to the table, anyway.

They usually don't.

This is why Carlos is currently dragging his finger along the surface of his bathroom mirror, still damp from his shower and now adorning the message: "PATRICE – WHERE IS CECIL'S HEART?"

Patrice, Night Vale's first puzzle, is a shy soul – Carlos hopes the reason she hasn't interrupted his verbal woes is because she doesn't dare, rather than it being because she doesn't know.

A few hours later, when he's grabbing a snack, the magnets on his fridge read: "HE WORKS IN RADIO, DEER". Dear, he mentally corrects. His As keep disappearing.

It's a non-sequitor and a non-answer in the way that only ghosts can, and Carlos sighs. "THANKS," he writes back, but his snack doesn't taste as good as it did.

A scientist is patient. It is the second thing a scientist is.

Carlos tries several other experiments to ascertain the location of Cecil's heart, and he doesn't really realize what he's doing until Cecil looks up from polishing his blood stones and says, "You've been very affectionate lately."

Carlos is sitting by the window. They're in Cecil's living room, and the chair Carlos is currently using is eye-catchingly ugly, yellow with bright green spots that Cecil proudly proclaims to be natural. Light streams in from the window, giving the room a soft glow, and Carlos is reading. "Mmhm," he says, engrossed in the scientific journal in his hands. "Wait – " he drags the word out, eyes quick over the page before he finally looks at Cecil, sitting cross-legged on the floor with hair in an impeccable pony tail, shirt inevitably halfway out of his pants. "I'm sorry, what did you say?"

Cecil smiles at him, like he thinks Carlos is the most endearing being in the whole world. "I said, you've been really affectionate lately."

Carlos blinks, mind still on structure of monogenetic volcanoes revealed – before he finally realizes what Cecil is saying, and his mind floods with guilt. "I'm sorry," he says miserably, because Cecil is shining, giving Carlos's behavior the best of intentions when they were in reality rooted in his rude, insatiable curiosity and an inability to ask a simple question.

"Oh, don't be sorry," Cecil says, worry tensing his brow minutely. "It's only, you know, I was talking to Marcella at work, and she said you might be overcompensating – which I said was absolutely ridiculous, of course, because you haven't even got anything to compensate for – but I just wanted to make sure everything was alright."

"I – " Carlos stammers. "Marcella? You talk to her about me?" is what he finally gets out, voice slightly squeaky, and it's so far from a proper response that he winces.

"She's the new intern. Lovely girl – her parents moved from Desert Bluffs," Cecil says the name with his usual acidic derision, "but you wouldn't think it to look at her." He suddenly gets very occupied with his blood stones. "Station Management – uh, they reprimanded me for mentioning you so often, and Marcella said it might help to talk to her about you first, and it has. She really is quite nice." He doesn't look up.

"Cecil," Carlos says, awkward and full of emotion, and Cecil finally meets his eyes again. Whatever he sees in them must calm him down, because he releases his death grip on the stones. "Nothing's the matter with me."

"Okay," Cecil replies, eyes soft. "Good." Looking at him, Carlos realizes he'll either have to man up or give up – and everything in him shies away from the mere idea of that loving, but heartbreakingly condescending look from Cecil, the one that says I love you, but you should know this, the one Carlos undoubtedly employs whenever they talk about mountains or the moon. Cecil looks so honest sitting there, afternoon light streaming in from the window behind Carlos and catching in his hair, illuminating the quietly peaceful expression on his face now that he knows Carlos is okay, and Carlos can't take it any more – he puts down his journal and moves next to Cecil, catches his lips in a kiss that the other man gives in to immediately. "Now?" Cecil asks, smiling wide.

"Yes," Carlos replies, fingers nimbly unbuttoning Cecil's linen shirt.

"Okay," Cecil says, lying back, and Carlos licks at the skin he uncovers – Cecil never wears undershirts – and kisses his way down Cecil's chest, starting with a generous kiss to his clavicle. It's taken time, to make Carlos comfortable with things like this, and it helps when he has something specific to focus on – which ends up being Cecil, for the most part. He laves at one of his favorite spots on Cecil, the little hollow between his pectorals, and something suddenly stops him dead. Lips are one of the most sensitive parts of the human body, Carlos thinks inanely, when his are resting there and nothing is stopping him from sensing the quick rhythm under his mouth, faint but unmistakable.

A heartbeat.

Thoughts race through his mind; memories of the first time he noticed its absence, the subsequent experiments … is it possible he only imagined the lack of it? Has it simply been another trick of the mind from Night Vale, odd, random and inexplicable, or has it somehow returned?

Cecil, ignorant of Carlos's internal chaos, coaxes his chin closer for a kiss – and Carlos, doing something Night Vale has forced him to, again and again, lets it be.

Even when they no longer need excuses or scheduled plans to see each other, Date Night is still a tradition Cecil holds fiercely on to, despite Carlos's best attempts to the contrary.

It's not that he hates dates – frankly, it's kind of amazing to walk down the street with Cecil, when everyone can see that he, "killed a cat"-Carlos (it was dead when he found it, okay), had found someone as incredible as Cecil. Rather, he hates who he becomes, reverting back years until he once again stutters and fumbles with his cutlery, eats popcorn way too loudly, and with hands always sweaty when Cecil takes them in his. It is ridiculous, but Cecil still becomes a little intimidating and impossible to impress across the table at Big Rico's, becomes the unsettling voice cooing over Carlos on the radio, all-encompassing and terrifying – even though Carlos has seen him in all kinds of moods at this point, at all hours of the day, and Cecil doesn't frighten him like he used to.

Carlos tries, though, because that's what you do in relationships, and it's gradually growing easier – today they're going to the showing of Little Shop of Horrors in Mission Grove Park, "encouraged viewing for residents of any age in accordance with the Treatment of Plants Intent on World Domination Act of '55."

He picks Cecil up at the studio. "Do you need a coat?" Cecil asks from inside, and Carlos nods gratefully. The temperature changes in Night Vale still throw him for a loop – he's already scientifically proven that they're more severe than even desert communities have a right to, but Night Vale doesn't listen to science very often. "Here you go," Cecil says, stepping outside with a smile and a coat for Carlos in his hand. "A coat for your coat."

Carlos shrugs it on over his thin lab coat, and grabs determinedly for Cecil's hand when they start walking, before his hand has time to get sweaty. Cecil grants him another smile.

"How was work? Marcella showed me this seal video that was unbearably cute," he asks, and Carlos remembers why he endures Date Night. It's because in the space of a few seconds, Cecil can calm him down, create an atmosphere reminiscent of sleepy-drunk philosophy discussions on the floor of Cecil's kitchen.

(Carlos doesn't think he's ever been that happy.)

"It was good," he says, and starts expanding on his research into the Red Mesa, Cecil nodding attentively beside him.

They end up making out through the end of the movie, but that's okay – he's seen it before.

"I'm telling you, that frog smell will not go away," Carlos says, unlocking his front door and flipping the light switch to show his modest apartment.

Cecil clucks. "Have you seen Auntie Aroma? She's terrific at vanquishing unwanted smells."

"Sure," Carlos says, watching as Cecil sheds his jacket and looks around. He's been here before, but not very often, and Carlos still feels like he should apologize for the journals and half-finished experiments littering every surface – as well as the mountain of dismantled clocks by the coffee table that he keeps forgetting to return to their owners.

But no, Cecil only turns to him with a strange, almost reverent light in his eyes and says, "You haven't rearranged," like the fact that Carlos hasn't bothered to move his couch over that weird stain on the carpet makes him a creature of benevolence.

"Uh, no," Carlos says, because it's true – he hasn't.

Cecil exhales a small laugh, and steps a little closer. "My beautiful Carlos," he says. "I love you."

It's been only a few hours since their last kiss, but Cecil is looking at him like he's an oasis, and Carlos is simply powerless.

He's tugged closer, and Cecil's hands rest easily on his hips. They slide into the kiss like stars in orbit, destined and inevitable, and Carlos closes his eyes, relishing in the feeling of Cecil's mouth under his. He breaks the kiss momentarily to toe off his boots and pushes Cecil down on the couch, straddling him. "What day is it?" he mumbles into Cecil's skin, lips wandering.

"Wed – nesday, Carlos," Cecil gasps, because Carlos bites down at the juncture of his shoulder before he finishes speaking. (He loves pain receptor day.) He lays a hand on Cecil's chest to feel his heart, because his safest addiction is feeling and listening to the beat of it, always rabbit-quick and eager at times like this – but under his fingers, Cecil's chest is silent.

It's so unexpected that it jars Carlos out of the moment completely, and he sits back a little, looking at Cecil with wide eyes.

"Cecil," he says finally, presses his hand down to check a final time. "Where is your heart."

Cecil blinks a little, and then flushes. "I – already? I never thought you'd ask for it so soon!" His hands tighten on Carlos's hips.

"What?"

"But I'm sorry, it's still over at the MacArthurs' house," Cecil continues, looking genuinely regretful. "I told you about Dylan falling victim to a librarian, didn't I? I could get it tomorrow, I suppose, but it's really too early in the mourning period."

The feeling of being confused, of being utterly lost is one Carlos has hated all his life – it's why he's devoted his life to understanding. Still, confusion is the only thing he's feeling right now, as if Cecil had suddenly started talking in the verbal equivalent of Webdings. "How?"

"Well," Cecil frowns, "I know for a fact I've introduced you to Lennon, our heart boy." Heart boy? Carlos gripes internally. "He usually moves them after an announcement."

"Cecil," Carlos says helplessly. "Out of towner." It's their shorthand for I don't understand, and Carlos invokes it as rarely as possible, but nothing is making sense.

"Oh," Cecil says, stopping the unconscious circles of his hands. "Well, I make an announcement – for example, 'Our hearts go out to the MacArthurs' – and then they … do. I'm sorry, Carlos, haven't you heard of this before?"

"Not literally," Carlos says. "So your heart is … not in your chest?"

"Well, when it's not with someone else, it is," Cecil says. There it is, that look of I love you, but you should know this. Carlos sighs, and Cecil notices. "Hold on," he says. "I think I have – I have my mother's, I can show you."

Carlos wordlessly moves over to sit beside him on the couch, and Cecil goes to fetch something small from his jacket, carefully wrapped in a leather cloth.

"Here it is," he says, voice hushed, as he sits down again, leaning into Carlos. "She left it to me when she died." He casts a glance around the room. "We should probably turn off the light."

"Okay," Carlos says, and goes to do that, feeling nervous. The room is plunged into darkness, only lit up by single rays of moonlight from the window. When he sits back down, he is careful not to jostle Cecil.

Cecil pulls at the string keeping the cloth together, and it folds away, revealing something small and glowing. Carlos gasps. In his hands is an orb, surrounded by a metal frame of black swirls, possessing the size and apparent frailness of an egg. The orb casts light blue shadows around the room, gorgeous interplay between its light and its cage creating a dynamic with a distinct presence, almost as if Carlos can feel Cecil's mother in the room with them. She feels like a familiar figure, suddenly, as Carlos studies the intricate pattern of black curls, and Carlos remembers all the times Cecil has mentioned her. He wishes she were still alive. He realizes that this is intimate, that this is Cecil's mother's heart – all of the love he's heard of, contained in one tiny radiant sphere. "It's beautiful," he says quietly.

"Yes," Cecil says simply. "I'd like to give you mine when I get it back from the MacArthurs."

Carlos's eyes snap up to meet Cecil's, gentle and alien when painted in this strange light, and he is speechless.

"If that's okay," Cecil adds, and Carlos surges up to kiss him, cradling Cecil's hands and the orb between them so it comes to no harm.

"Yes," he says. "Yes, of course, I'd be honored." He rests his forehead against Cecil's, looking down at their hands.

They sit there in silence, the heart casting its light over them.

A/N: title is latin for "conundrum of the heart". i figured night vale was the type of place where, when cecil says "our hearts go out to those who miss him", the means it literally. that spawned this fic. (also, i hope i got carlos's voice right. he's not the easiest.) also! say hi to me over on tumblr (i'm keptein there too), because i desperately need someone to talk night vale with, and i have a feeling you're pretty lovely.