Those aren't his eyes.
Sesshomaru knows his brother's eyes, knows them a bit too well perhaps. He knows their moods, their shades, the emotions that he often sees swirling through them. But these, the ones that he sees now as they cross blades once more, are not the eyes of his brother. Not the eyes that he knows, the eyes that he loves, as loathe as he was to admit it.
These eyes are pitiful, begging and screaming out for help. And Sesshomaru wonders, just how deep does this... affection perhaps? Attachment? That he has for his brother, run? He doesn't know, but he what he does is that it pains him to see his brother's eyes like that.
Save me, those eyes seem to beg. And Sesshomaru's heart constricts painfully in his chest with a longing to comply with that silent wish. But he can't think of anything, he can't think of a way to free his brother from this cursed sword's control; to free him from the blood lust that has claimed him and is controlling him. No matter how strong Inuyasha is, no matter how hard he tries to resist and fight it; it's too strong, he can't reign it in, can't control it.
And it breaks his heart.
"Every time our blades cross Sesshomaru, I know your every thought."
The thought of that damn sword knowing what he thinks, and more importantly, how he feels, disgusts him. These are his thoughts, and he would much rather keep them to himself; at least, until he can sort through them properly without his damn hurt messing with his judgment and his mind.
"Shut up you stupid sword! No one's listening to you!"
Once more, Sesshomaru feels that pain wrack through him when he sees that pitiful look in his half-brother's eyes. And he almost, almost, can empathize. But that's not in his character, so he'll deny that he even feels that way in the slightest. He's supposed to be cold, detached, regal, elegant; he's not supposed to let his emotions rule him, he can't be like his brother.
But this once, he'd like to let his emotions control him. He wants to listen to that little voice inside of himself that urges him to just let go of the careful façade that he'd cultivated for so many years; that no one so far had managed to even make a dent in. But he could feel it was chipped, it wasn't as perfect as it had once been. People have made their way into his heart and firmly into his mind.
Inuyasha is one of them. Rin is there as well.
He thinks back, back to what his father had said that fateful night. He had asked him, Sesshomaru, do you have someone to protect? And at that time, he didn't; and he had not believed that he ever would. He hadn't wanted someone to protect; why would he ever need someone to protect? The idea itself was ridiculous! Look where that reasoning had gotten his father. Sesshomaru had firmly rejected it and tossed the very notion aside.
Which begged the question, why did he now suddenly feel that his position on that issue had changed? It wasn't simply because of Rin; he had felt himself shifting before he'd met her. Definitely not Jaken either, that pathetic toad might be useful, but he was more or less a nuisance. However, he had proved his worth, Sesshomaru couldn't fault him for that; it was just Jaken's demeanor and manner that constantly annoyed him.
Besides, stepping on him and walking over the toad was a great stress reliever.
But that wasn't the issue here, the issue was his rather... confusing feelings about his younger half-brother. It wasn't so much that he hated him (in fact, Sesshomaru would have cared less; it was not his business what his half-brother did or saw), but more that youkai society dictated that half-demons like his brother were disgraces and were supposed to be exterminated to preserve family honor. However, Sesshomaru had never cared for that particular sort of thing; he was much more inclined to just ignore Inuyasha's existence.
His heart, however, wouldn't let him do that.
So he had done what he could, to at least keep his reputation. If he had too, then he would do his utmost to pretend that he did indeed despise his brother. No matter the cost to his own heart, he knew that youkai society would be hard on his brother; he would try and keep Inuyasha as far from it as possible. If feigning disgust and hatred was the only way he could do so, then so be it. He would rather deal with his own emotional pain then have to bear both his own pain and that which he had inflicted upon Inuyasha.
Damn it, the half-breed meant too much to him.
And that bastard sword was taking advantage of it. It was forcing him to continue to fight as hard as he could, simply to stay alive, pushing him; it was almost as if the sword wantedhim to kill his brother.
"You catch on quickly Sesshomaru."
Bastard sword! It took advantage of his hesitance to kill his brother, it longed to force him to kill Inuyasha; to taste the pain and heartache that it would cause him if he did so. This sword thrived on the pain and negative, dark emotions that would run through people.
Sesshomaru might be a youkai, but youkai are susceptible to pain as well. Just not in the same way that humans were. Long years had passed where the daiyoukai had searched out for that one youkai who would complete his existence; but his searching had proved futile. He might not have put his full effort into it, but he had looked sufficiently enough to know that they weren't out there. Or at least, he was looking in the completely wrong places.
That in itself was frustrating. But it wasn't Sesshomaru's main concern, right now, he was more concerned about his younger brother; he wasn't sure that he would be able to survive his loss. For one thing, Inuyasha was strong; much stronger then many noble youkai that Sesshomaru had met who were significantly older then his half-brother; another was that, though he hated himself to admit it, his half-brother was actually very beautiful. Not in a feminine sense, of course, but he was beautiful in his own way; Sesshomaru could admire beauty in all its forms, whether it be male or female.
"Haha! I will take that which is most precious from you!"
Only the slightest widening of Sesshomaru's eyes gave away the shock he was feeling as he leapt back from his half-brother. What was that sword planning? More importantly, what did it know that he didn't? He was quite sure that he knew himself and his mind very well.
Lingering on his thoughts, Sesshomaru quickly realized what it was that the damn sword meant right as Inuyasha charged towards Rin and Jaken; about to kill them. He charged forward prepared to kill him. But something in him knew that he wouldn't be able to kill Inuyasha, something was holding him back.
That half-breed... completed him.
That half-breed, his little brother, was his mate.