"Oh god, Cas…that's…oh…" Dean bucked and moaned. "God, yes!" he shouted as he climaxed, muttering a random mixture of 'god', 'Cas', and 'yeah' as he bucked through the aftershocks.

The corners of Castiel's mouth turned up slightly; an unfamiliar observer might have concluded that the angel was expressing slight but hard-earned approval of Dean's ejaculation.

Dean knew better. "Enjoying the view?" he asked.

"I…take pleasure in observing your satisfaction."

"You were taking pleasure in your own satisfaction a few minutes ago," smirked Dean, before growling in an imitation of Castiel's voice, "Fuck, Dean, fuck, fuck." Dean returned to his own voice. "For an angel, you swear a lot."

Cas shifted in the bed to pass Dean a box of tissues. "You didn't like my initial choice of vocalizations."

Dean rolled his eyes. "When you start chanting in Latin, I think you're about to summon something."

"Perhaps I was," answered Cas, with just a hint of wry humor in his voice.

"Please don't tell me that you've got some kind of orgasm summoning spell."

"It is less of an incantation, and more of a," Cas paused, "ritual."

Who said angels didn't understand humor?

The two men had been in a state of continual linguistic compromise ever since they had begun sleeping together, starting with preferred terminology for the sex act itself. Castiel had opened negotiations with a series of clinical-sounding terms. Dean rejected coitus on the grounds that it sounded like a rash old people get. He was also opposed to sexual congress, saying, "You'd have to ask Sammy for the details, but I'm pretty sure we don't want congress anywhere near our sex lives." He shuddered at the word intercourse, claiming it made Cas sound like the extremely old and unappealing woman who had taught him tenth grade sex ed, complete with graphic photos of STD-infested genitalia.

Dean had countered with a series of homespun euphemisms, but Cas had a tendency to take those literally, which was admittedly funny, but not exactly arousing. Cas declined a roll in the hay on the grounds that the nearest farmhouse was regularly inhabited by transients, so their privacy was not assured. Smoking pole had led to a lecture on the link between "inhalation of oxidized particles and respiratory cancers." The suggestion that they meet up for some afternoon delight caused Cas to arrive at the motel with what he assured Dean was the most delightful pastry the bakery had to offer.

A few terms were amicably rejected out of hand by both men. The Biblical terms know and lay with were agreed to be far too vague. Dean disliked the term lovemaking as "chick-flick bullshit" and Cas disapproved on the grounds that it was grammatically backward: ideally, sex made love, not the other way around.

The Shakespearean term beast with two backs appealed to both of them, but was ultimately rejected after some consideration. Dean concluded that the idiom referred to two people fucking face-to-face with no space between their bodies – a heterosexual missionary-position standard, but nearly impossible for anal sex unless one or both partners was extraordinarily flexible.

Initially, Cas had resisted using profanity. The words felt awkward and unnatural on his lips. But one morning he steeled himself for the effort and woke Dean with a husky whisper, "I want to fuck." Dean's moan, his immediate erection, his heavy-lidded arousal, had been reward enough for Cas to pursue sexual cursing with gusto. So the term fucking had become their most frequent referent. (Sam, showing incredible talent in the field of making exciting things boring, had later taken it upon himself to explain the word's etymological ties to a Middle English expression for plowing a field, causing Dean and Cas to add a range of agricultural metaphors to their sexual vocabulary.)

After depositing the sticky tissues into the wicker motel wastebasket, Dean flopped belly-down onto the bed, feeling weak and sleepy. "That thing you did, the uh-" Dean made a gesture. "That was good. Where'd you learn that?"

"The television," said Cas. Most of the motels frequented by the Winchesters had one or more pornographic television channels included as part of the standard room rental. Castiel had seen sex many thousands of times before – humans devoted so much time to the act, he could hardly avoid it – but prior to meeting Dean, he had never watched it with an eye toward positions or techniques he might apply to his own life. It seemed voyeuristic to observe live human copulation for his own gain, so the TV was proving a vital instructional tool.

"So I've been thinking," said Dean, lolling vaguely across the bed in a post-orgasmic haze. "You said your true form is the size of the Chrysler building, right?"

"That is the earthly object which most closely approximates my dimensions."

"I'm not as smart as Sam," Dean continued, in an apparent non-sequitur.

This disorganized speech was common immediately after sex. Cas simply waited for Dean to arrive at his point.

"I'm not as smart as Sam, but I can still do math and shit. It's not that freaking difficult. So I did the math and if we figure that a six foot tall man has a six inch dick, then your true form has a dick that's like eighty-five feet long." Dean tipped his head back. "That's really fucking intimidating, you know that?"

"I believe you are highly intelligent, Dean. You needn't defend your intellectual ability to me."

"So is that a yes or a no on the monster cock?"

"Your arithmetic is accurate."

Cas was not particularly subtle when he was being evasive and Dean knew the best strategy was to put on his best disappointed-in-you face and wait.

"Your arithmetic is accurate, but your assumptions are incorrect. You are presupposing that my true form has the same anatomical structure as a human male. This is false."

Dean considered this for a moment before his jaw dropped open. "No, no way, man. You mean you're really junkless?"

Cas pulled himself up stiffly. "I am not," he huffed in a dignified, offended sort of way, "junkless." He sounded slightly offended. "A comparison cannot be made."

Dean could always tell when Cas was getting prickly, because the angel stopped using contractions.

"My true form is beyond mortal understanding," protested Castiel. "You lack the vocabulary and in fact the neurological foundations to comprehend its composition!"

"Sure." Dean patted Cas on the head as if he were humoring a small child.

Cas narrowed his eyes in a glare that suggested imminent smiting, but his wrath was cut short by Dean's stubble rubbing against his neck.

"I have a request," said Cas after many minutes had passed. "I understand that you regularly use the name of God as a generic interjection to indicate emphasis, attention, or surprise, but I would prefer if you would refrain during our…fucking."

Dean nodded. "I get it, it's a little incest-y, right? 'Cause he's your Dad and yeah, that's a mood-killer."

Cas shook his head. "Many mortal civilizations have incest taboos to prevent inbreeding. Angels do not reproduce and so lack human instinctual sexual mores." He paused. "It is more that I do not wish to be reminded of my father's judgment."

"Why?" asked Dean in a teasing voice. He stood and waggled his softened penis in Castiel's face. "This make you feel unholy?"

"Neither your genitals nor their actions are unholy, Dean. Coi- fucking," he corrected himself, "is not inherently sinful."

"So, what's the problem?"

"Fucking is very…" Cas's lips pursed as he searched for the word. "Corporeal. It is very bodily. In my true form, I have senses far more subtle and penetrating than anything the human body could perceive, but the information does not evoke sensation or memory or emotion. When we fuck, I sense temperature and pressure, light and sound – and I experience these as a being with a body. I don't just notice; I feel." He shook his head, apropos of nothing. "It doesn't feel wrong," he said, his voice now drawn down to a whisper, "it feels like falling."

Dean couldn't figure out what to say and when he opened his mouth, what came out was, "It's still so hot when you say fuck," which he would be the first to admit was probably not the ideal response.

Cas looked confused and just a bit puppy-dog.

"Look," said Dean, trying to approximate a supportive boyfriend, "you said God loves humans, so feeling like one or wanting to be one now and then, that can't be a bad thing. You're still Cas, you're still an angel, and you're hardly the first guy to get weird thoughts in his head when he's fucking. You know Sammy used to apologize to skin mag models after he jerked off to them when he was like fourteen? That's just bizarre. And he doesn't know I know that, by the way."

"I have found it near impossible to arrive at a consistent moral stance regarding pornography."

Dean waved a hand as if to signal Cas to stop trying. "If you want me to lay off the god-talk, I will. I mean, there's feeling good and there's feeling embarrassed, and it's damn hard to do both at once."

"Thank you, Dean. And perhaps to ease the transition, I could make use of a ball gag to silence you the next time we fuck."

"What the hell have you been watching on TV?"

In case you're wondering, the Chrysler building is 1050 feet tall. If a 6 foot man has a 0.5 foot penis, then a 1050 foot man of equal proportions would have an 87.5 foot penis. I'm not sure if Dean was rounding or adjusting for shrinkage.