There are half-awake morning kisses, a brush of lips across Rodney's forehead and a whispered "G'morning" as John slips away to go back to his quarters in the pre-dawn light.
Sometime after John's morning run and around the time Rodney is ready to fling either an expensive piece of machinery or one of the incompetent morons who work for him out the window, John shows up in the labs with a fresh cup of coffee and when he hands it to Rodney, their fingertips slide together for a few fleeting seconds. When John leaves to go tend to military matters, Rodney straightens his shoulders and goes back to work, and when he says "you idiot" to the next timid lab tech to approach him with a problem, he's not quite as snappish as he was ten minutes before.
When the days and nights blend together into a cacophony of "not enough time, not enough time, not enough time" and they haven't seen each other for hours while John sorts out explosive power and Rodney tweaks the mechanics of the city to pull just a little more power from nearly-drained ZPMs, they run across each other in a hallway, with people scurrying to and fro around them. They stumble into the nearest empty room and kiss each other sloppily, hoarding up snatches of taste and touch and smell for the long hours still to come, breaking apart too soon when demanding voices crackle over their radios.
Other times, when the days seem endless simply because they are stuck in boring meetings all day, they find an empty corridor while walking from one conference room to the next, and use their lips to barter for things other than fifty crates of C4 ("What? It's useful.") or fifty new science personnel ("It's not my fault they keep sending such hopeless morons. ... Oh, fine. Can I at least get fifty crates of good coffee to help me cope with such brainless twits?").
Sometimes, when they have time for details, Rodney kisses John in the unsexiest places (an elbow, an ankle bone, halfway up his calf) and John shivers at the way Rodney makes every part of him feel wanted.
When the lights are dimmed and the city is quiet, Rodney tucks the blanket around them and kisses John's shoulder as they settle into each other's curves.
Sometimes, Rodney sits bolt upright in the wee hours of the morning and starts muttering equations to himself, and John grumbles into the pillow and throws out an arm to pull Rodney back down and mutters incoherently along the lines of "can't it wait 'til morning?" or "shut up" until Rodney kisses the corner of his mouth by way of apology.
Other times, Rodney mumbles frantic words that sound vaguely like "citrus" or "whales" or "John!" and John spreads a hand across Rodney's chest to soothe the fears that nighttime brings, pressing the warmth of touch into his skin until Rodney's heartbeat slows and he snuffles quietly, and John's lips whisper softly against Rodney's shoulder for a few moments before he drifts back to sleep.
Occasionally, they sleep all the way through the night—no flashes of insight or nightmares or emergency radio calls—until John gets up just before dawn and gently presses a kiss to Rodney's forehead.