"Your office is ridiculous, Mycroft," Sherlock mused as he tipped the antique chair onto its back legs so he could put his feet on Mycroft's desk.
"Take your feet off the desk," Mycroft replied without looking up from his paperwork. "You'll ruin that chair."
"You sound like Mummy."
That earned him a glance and a scowl. Sherlock grinned.
"Can't we just leave?"
"I have to get this finished. I'm sure you can entertain yourself for ten minutes."
Sherlock rolled his eyes and sighed dramatically, but shut up. After a few minutes, he started in again.
"Honestly though, the furnishings here are quite literally from the nineteenth century."
"Which is why I asked you not to rock on that chair," Mycroft replied sarcastically. "It's not as if I have any control over the interior decorating. Your Le Corbusier would look a little out of place here, although forcing a diplomat to sit in one would give me a definite negotiating advantage."
"Mm," Sherlock mused, "Being unable to see above the desk would be a bit demeaning."
"Precisely. To say nothing of the enforced relaxed posture. Look, I really need to get this done; ten minutes of silence isn't much to ask."
"Oh come on, Mycroft, you can concentrate on more than one thing at a time," he prattled on, distractedly. "You should at least get those curtains changed out for something you can see through. What's the point of having a view if you keep them shut all the time?"
Mycroft got up from his chair. Suddenly he, and not the curtains, had Sherlock's complete attention.
"What?" Sherlock asked, defensively.
"I asked you to be quiet, just for ten minutes, Sherlock. Since you're clearly unable to comply, and obviously fascinated by my decor, I'm going to assist you." He locked the door to the outside office. Unnecessary, probably, since Anthea had already left, but always a good precaution. He walked over to the window and removed the two long curtain tiebacks, hanging unused at either side.
Sherlock looked at him and stifled a huff of amusement. "Surely you don't intend to…"
"Have you ever known me to bluff?" Mycroft replied, bearing down on him in the chair. "As you pointed out, I'm not using these for the curtains; I might as well get some service out of them."
Sherlock made no effort to get away as Mycroft forced the curtain tieback between his lips. Somehow he even managed to look smug as Mycroft pulled it tight and fastened it low around his head. When he tied Sherlock's wrists together with the other strip of fabric, he didn't even have the decency to look interested. It wasn't until Mycroft forced Sherlock's wrists up his back and looped the free end through the back of the gag that Sherlock's brows shot up.
Mycroft stepped back and surveyed his work. Sherlock's head was drawn all the way back, held there by the pressure of his wrist position. His brother had already started to salivate around the gag. Perhaps he would have to replace the curtains; the tiebacks would certainly be unusable after this.
"You alright?" he asked his brother.
Sherlock nodded, as best as he could.
"Good." He reached between Sherlock's legs and felt the beginnings of an erection; Mycroft gave him a quick squeeze through his trousers. "Ten more minutes, then we can go back to mine and I'll give you my undivided attention."