Join Date: May 2010
Location: Within his Tomb in Nehekhara
Actually from what I've read Orks can somehow tell if another Ork has been infected by genestealer and will actually kill them rather quickly than let them spread. So Orks and Tyranids wouldn't happen in all likelihood. Tyranid alliances period wouldn't work just because of their nature. They consume anything and everything in sight. To ally with another race requires that both sides be able to reason to some degree as well as the ability to communicate, something the 'Nids can't really do.
As to the Tau being brothers in arms with Space Marines (at least the Chapters that don't have an individual Codex) is a little odd. I know some SM commanders that have faced the Tau in battle have developed some respect for the Tau and their ways of war but it's still a little strange to see them having the highest level of alliance. Though I can see SM commanders seeing the Tau as more preferable ally than the Eldar who have a long and sorted history of deception and manipulation. Maybe that played a role in GW's decision. Or maybe we're going to see something big develop in the Eastern Fringe in either next edition or the next Tau Codex, which ever comes out first.
We'll just have to wait and see.
'There's a fine line between not listening and not caring. I like to think that I walk that line every day of my life.'
Akatsuki13's Daemon Den