Originally posted by: riftwing
This is my take on the cursed seal thing. I think Kakashi said back at the 2nd exam that the cursed seal extracts chakra from the user at a massive level. When Kakashi sealed it, if Sasuke fell to evil goals the seal on the cursed seal would break and the cursed seal would take over. Sasuke was reminded of Itachi which is his goal and will do anything to accomplish as an "avenger" so the seal on it broke. Once that happened the seal extracted chakra from his body to power the chidori but because it used all his chakra he couldn't move anymore.
No, Kakashi said that the power of the seal depends on the will of the person with the seal on him, I don't recall him saying anything about Chakra consumption. If Sasuke decided to go the evil path, that seal would break and Orochimaru's power could be used as Sasuke's. But then, Orochimaru could switch minds with Sasuke and it would be all over.

mainva | aptigo | JTD out