A dull ache.
Persistent; unrelenting.
To Ed, the presence of this underlying pain was constant.
The loss of his mother, still so fresh in his mind; the loss of his brother's body, all his fault; the loss of his limbs, also his fault, his price to pay for his childish notions.
Edward Elric didn't feel ordinary pain.
He'd been shot, stabbed, kicked, punched, burned, drowned, torn limb from limb and killed, yes, killed-and yet none of it could ever eclipse that small, infuriating ache.
Some people would rather have their arm broken than a paper cut. Why? The arm, bruised and splintered and hurting like hell, over a small nick of the skin; Ed could never understand. They chose it because the paper cut lingered. It would hurt constantly, sting and itch and impede in the most mundane actions. Of course, so did the broken arm. It was all a matter of control.
Ed traded everything he owned for this ache. He gave his limbs willingly, his brother was taken, and his mother was received. He accepted it grudgingly, accepting his fate from the choices he has made.
The ache kept him up at night. It made him toss and turn in bed and knock flailing arms-metal and otherwise-into his lover. Nightmares were his punishments for even trying to sleep. During the day, when he let up his guard, it would slowly seep into the cracks and permeate his entire being until it had effectively halted his conscious mind. It put a stopper in the avalanche that was Ed's mind, filling the gap with memories and fleeting glimpses into happier times, just enough to make him long and ache and feel his pain once more.
His eyes would lose their flame. They receded into his face, empty and full of sorrow as he gazed upon something that was no longer there. His energy, seemingly always at a never-ending high, would deplete and leave him sitting, unable to even move. He would forget what he was doing. He would ignore those around him unthinkingly and without hesitation, only drawing back into the present with something surprising or unusually loving. His smile became a shadow of its former grin; anyone who had the misfortune to have seen it grace his boyish face soon wished they had never entered the room in the first place.
Ed felt no pain; only an ache, his personal punishment from purgatory.