Equivalent exchange was a rule that all alchemists lived by. You had to give something to get something in return. And, despite what some would say, it also was a rule you had to live by.

He could remember the first nights at the mansion, how he was at awe with the man's kindness. Who would have thought that a single father struggling to raise a daughter on his own would be willing to open his home to two orphan boys whom he didn't even know and who refused to share their dark secret? It seemed too good to be true, that someone would be kind enough to give up something for nothing…

And it was.

Edward Elric had known and understood equivalent exchange even at the tender age of twelve. It was one of the many hard lessons life beaten into his head time and time again.

Only a fortnight would pass before that lesson was reinforced - when Tucker had come for him for the first time. He could remember the encounter clearly.

He could remember the way he had been cornered in the small back room while his brother and Nina played outside in the yard. He could remember his protests dying as rough hands ran down the length of his body, removing his clothes, and gentle words of praise whispered into his ear, telling him what a good brother he must be to be willing to give up so much, coyly reminding him of that one base rule they both followed. He could remember his body being pushed firmly into the mattress, the weight of the man on top of him making it hard to breathe. And he could remember holding back the cries as Tucker had thrust into him repeatedly, forcefully taking what he owed.

He could remember equivalent exchange.

And it was with those unpleasant thoughts in mind that he forced a small smile on his face as he stood on his tiptoes, pressing his lips to the colonel's and interrupting the man's confession of love with a deep kiss before leading him to the bedroom.

As he lay back against the fluffy feather comforter, pulling Roy down with him, he prepared to make another memory. He knew that he would remember each kiss and sweet word whispered. He knew he would remember the soft touches, the warmth of the man's skin against his own. And he knew that he would remember the declaration of love that was said as the older alchemist entered him.

Edward panted as the dark haired man moved within him, confessions of love slipping freely from the man's lips inbetween heavy breaths, but the blonde said nothing in return.

After all, he didn't love this man.

He was simply remembering the rule. Remembering equivalent exchange, remembering to repay his debt.