Thought I'd toss this in...the Flood were nowhere around during Reach, the only place they saw it early was during The Halo Wars game and guess...that wasn't a Bungie game...to add the flood would ruin the storyline and the magic of the flood, because as we all know the Flood escaped on Halo CE because the Covenant were semiretarded(all heads over heels for the Great Journey) and ended up letting them out...plus the book Fall of Reach never had anything deal with "Oh My Great God!!! What the hech is that odd infected ship going this way!!!???" It'd be dumb and rather...well expected if it were to happen.......