Canon/noncanon aside, and taking place before the fall of the Empire, how do you think these two would interact?
Ahsoka, the Padawan that left the Jedi before Order 66, but trained under Anakin himself. Galen/Starkiller (Force Unleashed II), the hidden apprentice of Vader sent out to assassinate certain enemies, including Shaaki Ti. But later redeemed himself by not only forming the Rebel Alliance, but buying them time to escape (and in II, Starkiller captured Vader for the Rebels).
I ask, because when searching online, all I can find are "Who would win!?", which isn't what I'm looking for. And while I do know a bit about Galen, my knowledge about Ahsoka is rather limited.