Originally posted by: AssertnFailure
Originally posted by: Sapphire
It might be Sai because Sai seems to have some personal grudge against Orochimaru.. or maybe I'm wrong... can people without emotions have grudges?!

I can't really believe that Sai doesn't have emotions... maybe he just doesn't know what they are.. =/
Maybe oro killed sai's brother
Oro has killed so many ninjas and used them in his experiments so that could be right.