I had a theory. Palpatine told anakin skywalker that the sith have the power to save people from death, and that was the very power he used to bring anakin over to the dark-side with, a desire to save his wife from dying giving birth to luke and leia. At the end of revenge of the sith, the only reason that he survived hours after being burned in the lava, and he could breathe, is because the emperor sensed his distress and tapped into the darkside to keep his apprentice alive before he could rescue him and give him the famous robotic suit. The suit was not only there so Anakin could walk, but also so he could breathe through the Vader asthmatic breathing. Is my theory true? Did the Emperor keep Vader alive the time he lay on the lava river, burned?