Not only Uchiha Itachi, but Uchiha Sasuke as well. Orochimaru had truly lifted a rock only to drop it on his own feet.
He had once thought of using Feitao's blood for testing, attempting to protect his own cells from the ravages of decay, but Orochimaru could not pull it off. In the end, that idea remained nothing more than an idea, and he was unable to produce any substantive results.
Uchiha Itachi had planted a mental suggestion in him.
Chapter 270