"He took an ancient Sith practice of transferring the spirit of one person into another body and sought to put it into practice. I suspect his first target was Luke or perhaps even myself--" It wouldn't have surprised him if Sidious had been keeping him around all those years like a fattened calf, just waiting for the day he'd be ripe for the slaughter. In a way, it had been a blessing he'd lost the fight to Obi-Wan and been forced to break away from Sidious' control. "--but as usual, he had a number of plans put into place when that one didn't come to fruition.

He smiled in that wise way that most old mentors learned at some point in their time being a teacher. "The same way you learn anything else to do with the Force: control. You must learn to control it instead of the other way around."