I was writing this for a prompt but it was too long and I hated to cut it, so instead I finished it the way I wanted it done and I am pleased. This works well into the "Memories of You" universe because it is post-manga and Kagome is gone back to her time for good.
It was a simple extermination in a village not too far away and the two were on their journey home at dawn when they ran into the demon. It was a simple kill but while delivering the final blow, the demon's poisoned claw raked across Inuyasha's chest. Normally his fire rat haori would have provided protection but it was lying on the ground, Inuyasha having removed it because of the warmness of the day. The poison burned through his veins and he fought to remain conscious as Miroku helped him walk back to the village, missing Miroku's worried gaze at his condition. It was a long journey for the injured hanyou but they reached the village they called home by noon. Grateful to see Kaede's hut, Inuyasha allowed them to treat his injury as he lay back and succumbed to darkness.
ooOOoo
Sesshomaru's visit to the human village was a surprise. He had come with items for Rin several days before and no one expected him back so soon. He listened to Rin's chatter until she mentioned Inuyasha being sick. After a few questions, Sesshomaru decided he needed to speak with the priestess. Kaede and Miroku relayed the tale of Inuyasha's injury and Kaede let it be known that the fever and poison were ravaging his body and if no cure was found, she feared he would succumb by nightfall. Sesshomaru's cool gaze took in his brother's fevered and restless visage. With a nod, Sesshomaru stood to leave.
"I shall return before sunset."
Before Kaede could reply, Sesshomaru had left the tiny hut. Focusing her attention to the injured hanyou, Kaede, Sango and Miroku took turns cleaning Inuyasha's leaking wound and forcing fluids down his throat. Their hearts broke as he asked for Kagome in his fever dreams and all prayed to the kamis that Sesshomaru would not forsake his brother and he would return before dark.
ooOOoo
It took most of the afternoon but Sesshomaru was finally able to track down the witch he had been seeking. Takara was well known in demon lands for her ability to create cures for rare and potentially fatal poisons. As Sesshomaru entered the small hut, the tiny witch smiled and gestured towards a cushion on the floor.
"What brings you to this far corner of the western lands, my lord?"
Sitting, Sesshomaru regarded the witch. She had been in the service of his father centuries before and Sesshomaru was confident she would be able to help solve his current problem.
"I seek a cure for a poison." Sesshomaru described the creature that attacked Inuyasha and the symptoms he had been exhibiting. As he spoke, Takara whipped around the hut, pulling different ingredients and tossing them into a pot. His explanation finished, Sesshomaru watched as she stirred and bottled up resulting concoction. After giving him instructions on their usage but before she gave him the three bottles, Takara had a few questions of her own.
"This person for whom you seek this potion must be strong. Usually, this poison kills fairly quickly."
Sesshomaru contemplated for a moment. "He is my half-brother, a hanyou."
Takara's face wore a speculative look. "He must be strong indeed. A lesser being would have succumbed."
Sesshomaru stood, taking the bottles from the witch's hands. As he walked out the hut and into the sunshine, Takara heard him reply.
"He is my father's son."
OoOOoo
Inuyasha was in the midst of a fever-induced seizure when Sesshomaru walked into the hut. Miroku was doing his best to hold him down while Kaede was attempting to cool his body with cold compresses. Kneeling beside Inuyasha, Sesshomaru was momentarily surprised by the amount heat radiating from his body. With one hand, he forced open Inuyasha's mouth and pulling the stopper out with his teeth, he poured the potion down his throat. With his mouth being held closed, Inuyasha momentarily choked but he soon swallowed the potion. Gradually, the convulsions began to lessen and Inuyasha lay unconscious but still. Sesshomaru watched him sleep for a moment, his face showing no emotion. Giving the remaining bottles to Kaede, he relayed the witch's instructions
"He will need another bottle at midnight and the last bottle at dawn. If these do not help, there is nothing else to be done for him."
Kaede and Miroku could only watch in amazement as Sesshomaru took his leave. Both had questions but they knew there would be no answers.
ooOOoo
Inuyasha's fever broke a little while after he took the dawn bottle of potion. By noon, he was conscious enough to be fed a weak broth. Everyone decided it would be best to wait until his strength returned before he was told how exactly he had been cured. Sesshomaru hadn't been back to the village since that night and they weren't exactly sure how well Inuyasha would take to the idea of Sesshomaru being his savior.
After a week of recovery, Miroku finally explained what happened while Inuyasha was ill. To his great surprise, Inuyasha said nothing. Instead, he walked out into the forest and headed for Goshinboku. Leaping into the branches, Inuyasha settled in to think.
Sesshomaru's actions were unexpected. Never in a million years would Inuyasha have believed that Sesshomaru would go out of his way to help him, especially in a life or death situation. He wondered what the meaning behind this was. Why did Sesshomaru save him? Would he want something in return for saving his life? Before he could contemplate this further, Inuyasha felt the aura of his brother enter the area.
"I see you have recovered." Sesshomaru eyes coolly examined the hanyou.
Leaping from the tree, Inuyasha stood in from of him. "Yea."
The brothers stood regarding each other silently. Inuyasha wasn't sure what to say before he could come up with anything creative, Sesshomaru turned and walked away. As he reached the edge of the forest, Inuyasha called out to him.
"Hey, Sesshomaru!"
Stopping, Sesshomaru turned to look at his little brother. A bright red blush burned the younger's cheeks and only because of his demon hearing did Sesshomaru hear Inuyasha's next word.
"Thanks."
Before Sesshomaru could respond, Inuyasha had bound off towards the village. A tiny smile creased his face.
"You're welcome, little brother."