In the general realm of the trio's relationship, when a new game was proposed at the dinner table, or when they'd retired to their bed, it was Ed who broke the spontaneity to go and research what exactly would be needed, the best way to do it, and if it was actually physically possible without someone spraining something. This often left Al and Winry in an uncomfortable tableau, partially clothed, fully aroused, and threatened with death if they so much as tried anything before Ed gets returned. Unsurprisingly, the angry bitching between the two of them was frequently enough to distract Ed from his research, and thus everything took longer.
Winry tried to solve the problem by keeping a copy of "The Kama Sutra" on the bedside table, and Al found obscure books in various shops around town that promised Ed such-and-such an act could be done, and without an hour of preparation for five minutes of sheer enjoyment. But nothing seemed to work, and Al and Winry found themselves wanting to shake the other boy until they'd either been sufficiently satisfied or he died and they could have sex by themselves. But on a rainy afternoon they were struck by a brilliant insight, and Ed had come home to find two thousand-watt smiles that ushered him into the bedroom, stripped him, and held him down fast.
That had been just fine, nothing to get all flustered about; Winry wet and hot and yielding around him wasn't new and didn't merit any more study that he'd given it the first time around...until he felt slick fingers reaching down between them, caressing the base of his cock and following it up until those fingers joined him inside Winry.
He didn't have time to make any sort of surprised noise, however, as Winry dug her fingers in his hair and kissed him with a ferocity that said he was going to stay right where he was, and in a second Ed knew he had no other choice, not in the whole world, because Al was spreading Winry apart and then he was...
...he was...with his...oh god, oh GOD..
And Winry shrieked, digging for purchase in Ed's automail shoulder, Al arched his back to finish the entrance and groaned, and Ed felt his brother's cock rub against his own, both buried deep inside their female lover, their eyes met across her shoulder, and he was utterly gone.
There was a lot to be said for experimentation, Ed thought later, when Al was curled up in his arms as Winry fussed in the bathroom.
"Dammit, Al!" Winry's voice cut through their afterglow. "You didn't use enough oil! I'm going to be sore for a week! I told you not to forget!"
Well, Ed amended his previous though, there was a lot to be said for experimentation and a lot of lube...which they would have had if he'd been allowed to do some homework before they attacked him.
Honestly, he grinned and shook his head, what would they do without him?