They don't sleep together often.
Oh, they sleep together quite respectably often, thank you very much, but rarely will they spend the night together. By their age, they are accustomed to sleeping alone, and it reduces the chances of being caught.
So, whenever passion has given way to tenderness and then sleepiness, that night's guest will depart for his own bed. Blake thinks they're each the guest roughly half the time. Mortimer knows he's wrong (but doesn't say so).
Sometimes one or the other won't leave, and when this happens, he will not be nudged to. Other times, one will start to get up, only to be stopped by a hand, or a whispered "Stay."
After Egypt, Mortimer won't let Blake leave his bed for at least a week. Blake keeps him prisoner for much longer after Ardmuir Castle - in fact, things only go back to normal after Mortimer goes overseas again and returns.
On at least two occasions, he has woken up to find Blake in his bed when he hadn't been there the previous night (He doesn't have the slightest chance of pulling the same trick without waking Blake (he's tried)).
They're both quiet in bed, instinctively and by necessity - luckily, neither of them is particularly inclined to be loud. They do talk. Blake does, eventually, work himself up to dirty talk - but only in very rusty Welsh. Mortimer doesn't mind in the slightest.
(Which does result in his becoming quite flustered when they find themselves seated in a train carriage with a pair of Welsh speakers. Blake clocks him instantly and is hugely amused.)
Mortimer has evicted Blake from his bed exactly once. He came crawling back the next night, was welcomed in, and they never speak of it again. Both privately resolve never, ever to repeat that.
When Mortimer returns to his body, he refuses to sleep in his own room for weeks. It feels unfamiliar, violated. Blake is home.
("He never set foot in here, love, I swear it.")
Hotels pose a slight problem, in that people are more likely to come in, for any number of reasons. Sneaking in and out is also more conspicuous. They handle these on a case by case basis. Mortimer leaves that up to Blake - it's his trade, after all.
There have been much worse places than hotels - caverns, rocks, wilderness. Starry skies. Freedom. A lap makes a better pillow than eiderdown.
Mortimer has a tendency to roll around, but Blake likes the weight of him, so that's all right. He falls out of Blake's bed once, and they decide it is a minor miracle that Mrs. Benson didn't wake up. (She did. But nothing else happened, so she noted the time, in case it was some horrible robber or madman and the police would need it, and then she kept right on pretending to sleep until she actually snored).
Coincidentally, Blake then gets a slightly bigger bed. He's not as young as he used to be, and his back is starting to go, and the extra room is healthy… what? Don't look at him like that, Philip, damn it.
Mortimer thinks Nasir doesn't know. Blake is under zero illusions.
Mortimer hates Blake's alarm clock with a passion only outweighed by the one he has for Blake.
("Answer me, Francis - did you bring that in with you?"
"I told you I needed to wake up early, old chap-"
"I've had enough. Henceforth, you must choose between me and that miserable contraption!"
"I'm afraid that's the hill I die on, dear.")
Nightmares are a matter of course, but they both know each other better than themselves - when soothing words are called for, when a rough "Snap out of it!" Sometimes a shoulder, usually just a presence.
Blake privately worries about red hairs in the bedsheets. But if it comes to that, it's probably already too late.
Mortimer does, in fact, have a dressing gown. He has three, and has worn them a grand total of five times between the lot of them before they were inevitably appropriated by Blake.
("I'll report you to Kendall for possession of stolen goods."
"But you never even wear them!")
Blake likes the foggy nights. They feel safer. Mortimer likes the clear nights, when they can look out the window and see the stars. Sometimes they can't sleep, and go to look at them together.
Blake can tell the time by the stars - a trick he picked up in military training. Mortimer can only tell the seasons, but he knows each class of star by name and spins the stories of their fiery lives to Blake, who more than half believes him.
There's a particularly large one visible from Mortimer's window, and in some irrational way Blake thinks of it as their guardian. Mortimer says it will die soon.
("What's soon, to a star?"
"A few million years, give or take.")
Then that's all right, by Blake's calculations. It's reddish, like his lover's hair, and it means they can be happy in any bed it shines on.
No, on second thought, they sleep together quite often.