I'm reviving this thread again... OH my god, I love TB. It's so sad, and it makes you think -so- much. I just read TB a few weeks ago (borrowed it from a friend), and I also just read X.
Personally, I think Sei-chan did love Subaru the whole time, but he didn't know what love was and how it was supposed to feel, and so it was easy to convince himself into believing that he didn't love Su-kun. After all, at one point he says in the that he assumed from the beginning that he would win the bet. The whole bet thing was Sei-chan trying to come to terms with his feelings and understand them. But that's just me.
Somebody mentioned something about Subaru being a puppet and disappointing Sei-chan... Well, yes, Subaru is not a perfect person; he needs to grow a spine desperately, but that's no reason for Sei-chan not to love him. Yes, Subaru is flawed, but people do not have to be perfect to be loved. After all, Subaru loves Sei-chan, and Sei-chan is as evil as they come.
And I've said this in another thread, but Clamp has a special place in hell for the empty speech bubble in volume sixteen of X... The speech bubble that should have Sei-chan's confession of love. Gah!
Oh, and if anyone wants come text translations of all seven manga volumes, I have a link... They're fan translations, but they're not bad... She also has translations of X up to volume sixteen, along with RG Veda. They're not the same as having the manga, but... Actually, I've yet to read the RG translations... I'll probably do it over Christmas.
http://www.jahannam.net/