I have a tangential question about the parallel duel that occurs in ROTS between Sidious and Yoda that I’ve wondered about.
I am not a Star Wars fanatic, so I haven’t read the novels from the “Dark Empire” expanded universe, or any of the trilogy novels, for that matter. I really have only a scant understanding of some of the events that serve as padding for what went on in the two trilogies. I do know that even now, very little canonical information exists about the histories of either Palpatine/Sidious or Yoda. These two characters in particular have a background shrouded in mystery, and yet when Yoda enters Sidious’ personal chamber in ROTS, they exchange a few interesting lines which would lead the viewer to believe that these two go back together somehow. They share a sort of knowing jeering for one another, as if that wasn’t the first time they’d met, and then Sidious says to Yoda after knocking him out with lighting: “I have waited a long time for this moment, my little green friend.”
Not only is Yoda 900 years old, but Sidious has also (at least in the EU) extended his life through the use of the Dark Side to regenerate his body/spirit over the years. So far as I’ve been able to find, there is no indiciation of when Darth Plagueis actually lived, so there’s no frame of reference to compare when Sidious murdered him. Ostensibly, Palpatine was born some eighty years before the original trilogy.
My question is this: is there any EU canon which sheds any light on possible previous encounters between Yoda and Sidious?