User blog comment:Derax-Pagani/Fairy Tail Chapter 494: The Hill Extending Towards Tomorrow Review/@comment-130.105.225.146-20160716235523/@comment-7418318-20160717081413

But now he's dead and aware of it. Maybe the reason why he switched sides died along with his actual body.

Not that I'm actually hoping for Serena to switch back to Ishgar, on the contrary, but I'm afraid we can't completely rule out the possibility.

Though thankfully as Ur has proofen, the Historias are subservient to the caster's goals so that makes it that much more unlikely for Serena to turn against Alvarez even if he wanted to... not impossible since he might have the power to break free (or Rufus or Mest might twist his mind around) but rather unlikely.