Why is the planes walker Sorin B/W when vampires are mostly B/R?
In the story sorin created avacyn to create a balance between light and dark. While on Innastrad sorin believes a balance must be matained so the dark i.e. vampires won't devour all the humans. So he's a B/W plaineswalker. Both light and dark. Hope that helps.
It does, actually. Thank you.
He was supposed to be hated among vampires, outcast or betrayer so to speak. So WOTC made him so he wouldn't really work well with vamps