One more Inuyasha one-shot for you, this one's pretty short
He felt his human half fall asleep, but did not feel like following just yet. The rest of his pack was not back yet and someone had to keep watch, he would not leave his new mate unguarded. The raging emotions of the last few hours were what had brought his demon half to consciousness, and with both halves of his soul he had claimed Kagome as his. She had fallen asleep afterwards and his human soul exhausted, content, at peace for once in his life had joined her in slumber. He continued to watch her while his ears kept track of what was happening around them. Thought and speech did not come easily to him in this form, he ran more on instinct and emotion. The first few times he had emerged he had been wounded, angry, scared; in the middle of a battle his first action was always to fight, kill, protect himself. And since he was not a complete soul it took so little to send him over the edge, to a place where he did not remember himself. Here and now he was just as sane as he was on the nights his human half held the reigns, though different in mind and body.
Sango walked into camp exhausted, Kirara trailed her paws dragging and Shippo sound asleep on her back. Miroku on the other hand was decidedly upbeat as he led the group into their campsite, irritating Sango to no end. That was the last time she would go with him to pawn off the goods he received for 'dispelling an evil black-cloud'; it had sounded so easy when he suggested it, not like the several hour affair she had just been dragged through. She had always know the Monk was a smooth talker when it came to convincing some ignorant noble to pay him for his services—or when he wanted a pretty girl in his bed. But somehow she hadn't realized that he was also a shrewd bargainer and would not accept any price for his merchandise without haggling for hours. Sango was so tired she bumped into Miroku when he unexpectedly stopped, "What—"she started irritated, then noticed the perverted grin on his face. Looking to the other side of the fire she saw Kagome asleep on her bedroll, the fire-rat robe spread over her. Sango's jaw dropped, snuggled up next to the girl also under the fire-rat robe, his arm thrown over her, was Inuyasha. Miroku snorted in amusement and started to say something to her when Inuyasha sat up and looked at them.
The fire glinted off of his blood-red eyes, and the purple stripes on his face stood out in high relief. Sango gasped, Miroku swore and positioned himself in front of her his staff held at the ready. "Kagome!" he hissed, trying to either warn her or see if she was okay Sango couldn't tell. Inuyasha moved to a crouch, eyes fixed on Miroku and fangs bared, a low warning growl rumbled in his chest "Mine!" He snarled; and suddenly Sango saw the situation in a different light. She knew a lot about demon behavior, it came with the territory of being a slayer. She could, for instance, tell the difference between a demon in the grip of bloodlust and one about to pound a stupid rival male into the ground when he tried to take something that wasn't his.
"Miroku!" she hissed warningly before he could do anything stupid. She looked again to make sure. Kagome was unharmed, sleeping peacefully, and Inuyasha had not moved to attack, though a warning still rumbled in his chest. He had not even been acting in a threatening way before Miroku had panicked and brought his staff up to fight. Even more telling Kirara didn't seem concerned at all, and the two-tail would know if they were in danger. She grabbed Miroku pulling him back and out of his aggressive stance while carefully keeping her own gaze from Inuyasha's. "It's not what you think." She whispered urgently, Miroku looked at her like she was crazy. "Just calm down and look at them." He looked and Inuyasha snarled again. "Whoops, okay so don't look. Just… here—come with me and I'll explain a few things to you." She pulled him to the opposite side of the fire from Inuyasha and Kagome trying to stay as far away as possible without actually leaving camp. "About demons?" Miroku questioned. Sango snorted in exasperation. "About males."
Inuyasha relaxed as the human male backed off, he was pack, but not to be entirely trusted around the females, still it looked like the human's mate had him under control for the moment. He looked down at his own mate, she had noticed the lack of warmth at her side and still half asleep, her hand quested over the spot he had been lying in searching for him. He lay back down beside her, his head propped up on one arm so he could still see her clearly—and keep one eye on the rest of his pack. Kagome's hand finally found him, "Inuyasha" she whispered. He smiled, "Sleep" he told her, his voice rough as it always was in this form.
Hearing his growling voice Kagome woke more fully stiffening, her hand fisting on his chest. She opened her eyes tilting her face slowly up and looked into his own very red ones. For a second she stopped breathing and he smelled the wash of fear that rolled off her. Inuyasha held himself very still, not betraying how the scent roused his bloodlust, he would never hurt her, still… he hoped she wouldn't run. Kagome's eyes were wide with shock her breathing rapid. He found himself despairing at her fear, Kikyo had never accepted his demon form either, if Kagome rejected him… but she didn't try to get away from him, didn't call for help. As they lay there unmoving staring at each other her breathing and heartbeat slowed to a more normal pace, her eyes softened, losing their fright… the demon looking down at her dared to feel hope.
Slowly, as if afraid of startling him, she reached a hand toward his face hesitating for an instant then gently running her fingers along the stripes on his cheeks. Glancing into his eyes for a second she then traced a single finger down the length of his fang. Elation roared through him as she slowly explored his changed features—she accepted him! Moving slowly as she had he grabbed her exploring hand with his own, she started, glancing up into his eyes before relaxing. Slowly, very slowly in case she jerked away, he brought her hand to his mouth, their eyes stayed locked to each other. He opened his mouth bringing his fangs down on her fingers until they dented but did not break her skin, she did not try to pull away, and he could read the trust in her eyes. He released her hand and she let it drop to his chest, he smiled at her. "Sleep" he told her again, and this time she did, closing her eyes and snuggling into his chest. She breathed a contented sigh, and her muscles relaxed into sleep. Inuyasha wrapped his arms around her and pulled her as close as he could, his demon half was settling bathed in her acceptance, and trust. The knowledge that she knew each part of him, loved all of him, left him with a feeling of completeness he had never known. The peace of it let him fall into sleep with her as the halves of his soul merged into one again.
So my thoughts on this are that when Inuyasha is either fully human or fully demon he not quite a complete soul. He is rational to a point, and sane, but his thought process are altered. That is why he seems more emotional while human and more easily sent over the edge when demon - not because humans are more emotional or because demons are naturally bloodthirsty - but because he is not entirely whole.
That's why I imagine he always goes a bit crazy in demon form, he suddenly finds himself hurt, and being attacked, most peoples response would be to lash out, but he only ever hurt his enemies. As for those times he went after his friends, he only ever did that when someone unnaturally brought out his demon, like with the Shikon jewel.