ok i was wondering about what caused inuyasha and sesshoumaru to hate eachother, for real. i think i might have heard or seen in the anime that sesshoumaru wondered why inuyasha couldnt aid him in battle and didnt show cuz he was pinned to the tree. but im not for sure. does anyone know the truth?

I don't know for sure, I may be mixing these thoughts with what I have read in various fan fiction(so not facts). I think Inuyasha's hate for Sesshoumaru is the fact that he never acknowledged his existence(as his brother), that he always acted like he didn't exist, and never helped him when he was in trouble. It may just be that he felt that he did have a family member alive, that he wasn't alone, but then having that family member turn him away or completely ignore his existence made him feel alone, which made him angry. Maybe?

As for Sesshomaru, it might just be because Inuyasha's life, his birth, lead to the death of his father(the man he saw to be the strongest person around). He may also see Inuyasha as being a disgrace to his family, his name and lineage. These are just my guesses, which means there is a good chance I am completely wrong(laughs) Sesshoumaru hate's weak things, and sees humans as being weak, which Inuyasha being half human, would make his families name have some weak person in it. It's all kind of difficult and writing this out made me confuse myself(laughs) Ah hopefully what I wrote made some sense .

I can't give you an exact answer to that question but I can give you my own theory.

From what I have seen of the anime and of the movies it would appear as if Sesshoumaru hates/dislikes his brother due to the fact that his father not only died saving Inuyasha and his human mother but also gifted him a powerful sword (the one that Sesshoumaru wanted).
And possibly in is his eyes it would have been seen has his father saying that a hanyou was better then him.

Now for Inuyasha's side I would say mostly like it was due to the fact that he had a living relative while his mother was still alive yet they never came for him even after his mother had dead.
I believe in an anime Inuyasha had blamed Sesshoumaru for causing his mother's death, though I might be cross referencing an fanfiction on that.

Please remember that the third movie is not canon. None of that was ever in the manga.

the only real answers that can be given is something similar to this, (canonwise)

Inuyasha wanted to be acknowledged, as a demon, thus went after the shikon so that he could gain power from it. Sesshomaru wanted Tetsusaiga, and it just so happens that Inuyasha has it, in the beginning, it's almost as if, Sesshomaru thought, that Inuyasha wouldnt have remembered him, this speaks to the fact that they must not have been around one another nearly at all.

B/c of the fact that the 3rd movie is not canon, and some of the anime was filler, you can only really go by the manga. All we know is that Sesshomaru has an abhorrence for weakness, not necessarily hanyou. But he does seem to view Inuyasha as weak and unworthy, and thus does not like him.

But we can logically assume that whom ever Inuyasha needed/wanted acknowledgment from wasn't necessarily Sesshomaru. While fanfiction, loves to paint it so that Sesshomaru's a racist against hanyou, more often then not, Sesshomaru does acknowledge Inuyhasa, as 'Little brother.' it's usually in a mocking way, but he does realize and state often that inuyasha is his little brother.

Inuyasha doesn't seem to care for Sesshomaru, or what he thinks, says or does, but it's never shown just WHY inuyasha hates Sesshomaru. Considering he wanted to become a full demon when he went after the Tama when Kikyo had it, i would assume it's because he envied his older brother for what he had and was.

ie:

Omg r0o. That picture makes me smile. xD

*This comes based on a mish-mash of knowledge from the anime and manga (honestly it's impossible for me to separate them in my brain at this point...*

Here's what I think you're looking for:

- Sesshomaru is a demon racist. He doesn't think humans and demons should mix. When Inuyasha was young, he likely treated him with complete indifference/apathy.

- Sesshomaru's father fathered a half-demon and then gifted the baby Inuyasha his most powerful sword - Tetsusaiga. Sesshomaru didn't know this at first, hence why when we first meet him he is searching for the sword.

- This revelation pissed Sesshomaru off (understandable so). With his father already dead, he turned his anger on the next best source - Inuyasha.

- When Sesshomaru did actually need Inuyasha's help defend his father's kingdom in the war, he'd already gotten his ass nailed to a tree by Kikyou so he was of no use to him.

- On Inuyasha's side of things, not knowing this history, Sesshomaru comes off as a pompous, arrogant jerk. It's no wonder they hate each other!