ok...this is a list of why i hate him...there's no particular order, so just read through...the spoilers are marked at the bottom...the spoilers are considered anything after Yui becomes Seiryuu No Miko (on the Nakago section, anyway...)
non-spoilers
he's just so ugly
his voice is ugly
his hair is ugly
he doesn't like Hotohori
he wants to kill Hotohori
he doesn't get along with Tamahome
he plays with Yui's head
he made Yui hate Miaka
he made Yui Seiryuu No Miko
he doesn't care if/when his fellow seishi die
he helped Yui plot against Miaka, like, 15 times
he uses Soi as a mere sex object to raise his chi
he wears an earring in each ear...that's enough to make me shiver...yes, i know Tasuki wears two earrings too, but he does it with style
**SPOILERS**
he kissed Tamahome (my sweet)
he licked Tamahome
he has slightly homo-erotic tendencies
he pretended to rape Miaka
he sent out a fake Taitsu-kun...that was SO evil
he killed Hotohori
he (indirectly) killed Nuriko
he made Tamahome attack Hotohori and Miaka and all the other Suzaku Seishi
he told Soi that he didn't love her...VERY bluntly
he killed Tamahome!!!! NO!!!!
he (indirectly) killed Chiriko...his death was the most amazing thing!
he (indirectly) killed Mitsukake...nobody cared about him anyway, but still...
he made Suboshi kill Tamahome's ENTIRE family...NOOOOOO!
he (indirectly) killed Suboshi
he (indirectly) killed YUI!
he lied to Yui, making her think that she was raped for about half of the whole series!
he killed his OWN MOTHER...you just don't do that!
he sent Aishitere on a suicide mission
he killed Aishitere...twice!
he lead 87589324982 rape attempts against Miaka
he sent Amiboshi to screw up the entire suzaku calling ceremony