Reciprocity

rec•i•proc•i•ty: the quality or state of being inversely related

He had to wonder, sometimes.

He held the blade in his hand, watching as the moonlight played across its deceptively nicked and rusted metal.

Unexpectedly, a wave of bitterness seized him. This blade was the cause of everything.

The legendary Tetsusaiga.

It was made from his father's fang mere hours before his father died.

It could kill a hundred youkai with one swing.

It destroyed his brother.

Myouga had explained it to him one day: when one blade of such power is forged, another, opposite blade must be forged as well. Otherwise, the balance of power would be too greatly disrupted, and all hell would break loose. Possibly literally.

Reciprocal blades with reciprocal natures: one kill a hundred, its counterpart resurrects a hundred.

But for the blades to balance properly, one must have a nature exactly opposite the other, or the reciprocity fails.

A blade that seals away savage bloodlust must have a counterpart that seals away gentle compassion.

Tetsusaiga had been forged for two reasons: to be the deadliest blade in existence, and to contain the bloodlust of a certain half-youkai.

Its counterpart would, therefore, also have a dual purpose: to be the only blade known capable of resurrection, and to contain the compassion of that half-youkai's brother.

No wonder Sesshoumaru hated Tenseiga so much. Inuyasha didn't know how he'd react to having his personality altered against his will.

Come to think of it, his personality had been altered – Inuyasha may have a wild streak, but he was hardly a bloodthirsty killer. Had his savage tendencies not been sealed, a bloodthirsty killer is probably what he would have been. As for personality altering, he was an infant when the swords were created. He didn't remember a time when he wasn't like he was now.

Sesshoumaru did. The bitterness in his older brother's eyes was more than enough to tell Inuyasha exactly what Sesshoumaru thought of personality-altering swords.

Pausing, Inuyasha stared at the blade he held, eyes widening in realization.

Tetsusaiga only contained part of his savage nature. The half-youkai still had a not entirely undeserved reputation for violence.

Tenseiga, then, only contained part of Sesshoumaru's compassion?

He could show more of it, then, Inuyasha thought bitterly.

But didn't he? The older youkai had, after all, saved that little girl. Come to think of it, Sesshoumaru had also stopped him from running rampant when he'd lost Tetsusaiga and fallen into bloodlust.

Was that compassion?

Why did Sesshoumaru keep Tenseiga, if he hated it so much? If he destroyed it, the balance between the blades would be destroyed, and Inuyasha knew his brother wasn't stupid enough to let that happen. But why didn't he just leave it behind?

Even as he thought the question, Inuyasha knew the answer. It was for the same reason that he would never part with Tetsusaiga – the possibility of another wielding it with ill intent was too great a risk to entertain.

Still, the half-youkai sorely wished that he could see Sesshoumaru without the Tenseiga, for once.