"Once a month, I turn human" Inuyasha mumbled from behind Sesshoumaru's sleeves "on the night of no moon."
Sesshoumaru had heard of this plight of the hanyos. The most dangerous time for them was the time they were human. He had also heard that they could lose themselves to their youki. When that happened they had to be put down as nothing could bring them back.
He looked down at the child curled in his arms, Inuyasha had fallen asleep. Gazing upon the sleeping face of his half brother, who in this moment looked so much like the woman he had loved, he made the decision that he would find a way to keep that from happening.
As dawn broke Inuyasha once again returned to his half demon form. Sesshoumaru could sense the youki in his small body was the most powerful he had felt.
With his youki returned to him, Sesshoumaru had him try again to pull his youki into his fingers. Sesshoumarus fingers glowed green with his dokkasou as he swiped at a nearby tree, rending it in two, Inuyasha tried several times before he suddenly cut down the sapling before him.
They practiced for much of the day, then they hunted for dinner.
That evening, as Sesshoumaru sat leaning against a tree, Inuyasha came over and lay down with his head on Sesshomaru's leg before promptly falling asleep.