Superficiality. Ashara is a dark Inquisitors greatest triumph, as he manages to wrap around his finger a Jedi, and a pretty powerful one with it, control her, make her do his bidding through seas of blood and massacres and in the end persuade her that *its all for the greater good*. Poor thing bleats for you to make her the vessel of your legacy, pathetic, really, but oh so useful. She will go -in good faith- all over the Galaxy, killing your enemies of the moment , swearing you are not what you are so obviously are. Oh, the possibilities... Dark side apprentices are a dime a dozen, suffices to go to Korriban and pick one of the dazed survivors, or bribe good master Harkun to mold one to your desires, hardly a problem for a dark lord. You want your Xalek, you can keep your Xalek.