Usually, when the Fullmetal Alchemist appeared in Colonel Mustang's office, it was because some crisis was imminent, ongoing, or immediately past. He tended to drag trouble after him on a leash, that way.
However, there were a few times—like now—when Edward would show up in Roy's office when nothing at all was going on. In fact, he generally preferred times—like now—when most of soldiers had duties that called them elsewhere, and the two of them were, if not alone, certainly under less surveillance than usual.
Roy smiled slowly as Edward approached his desk, his usual careless pose turned into something... challenging. He did so enjoy these little interludes.
"Where's Hawkeye?" Ed wanted to know, glancing around.
"Attending an inspection," Roy replied. "Alphonse?"
"Visiting Alicia." Ed tossed his braid back over his shoulder, and smirked at Roy.
"I believe I have a couple of hours free," Roy murmured, propping his cheek on one fist and looking at Ed through his lashes. "From the looks of things, so do you. However shall we pass the time?"
Ed grinned, and stalked towards the desk. "You up for it, old man?" he asked. "Wouldn't want to wear you out after all."
"I can keep up with any insolent brat," the Colonel informed him haughtily, but still smiling. Hawkeye would be furious if she found out what Roy was doing with Edward in his office. In fact, Roy could think of half a dozen reasons he shouldn't do this, but somehow, looking at that hungry smile on Ed's face made them all melt away. "What I may lack in quickness, I more than make up for in experience."
"Ha. Bring it on!" Ed grinned, shrugging off his coat and leaning over, planting his hands on his desk. "Come on, bring it out. I know you've got it hidden in your desk somewhere!"
"Of course." Roy took the time first to unbutton his shirt, slowly and casually, and roll up his sleeves. Edward watched him closely, and he could practically feel the younger man's impatience, which of course only heightened his enjoyment. This was their little ritual, after all.
Ed's golden eyes sharpened with avid impatience as Roy finally reached into his desk drawer, to where he'd hidden the valuable object under some long-neglected paperwork... oh, yes.
"I'm black," Ed informed him as he pulled out the chess set, unfolded the board, and began to set out the pieces.
"As usual, Fullmetal," Roy drawled, arranging the ornately carved pieces on their squares. "You should practice some variety."
"I like black. Black is cool," Ed said. Roy made a vague wave with a rook, and Ed hooked his ankle around a chair and drew it up to sit at his desk.
"There's your first mistake, Fullmetal," Roy began his usual lecture, "foregoing any possible strategic advantage in the name of a trivial vague aesthetic preference—it's no wonder you're so easy to defeat."
"Hey. Watch me beat your ass again, old man! And it's not trivial, it's a psychological edge."
"Against the weak of mind, perhaps, but not..."
Hawkeye would probably kick his ass if she found him playing chess again instead of doing the paperwork. But it was worth it.
"That game sucked," Edward groused, kicking the leg of Roy's desk. "It only lasted barely half an hour! Hardly even worth sitting down for!"
Roy shrugged as he stood from his chair, tucking the set away again. "You were in rare form today," he said. "If you're so bored as all that, why don't we have sex instead?"
"Not on your desk I won't," Ed groaned. "I don't want to have to explain how I got papercuts in those places again."