User blog comment:FairyRaven/Fairy Tail Chapter 397: Steel, Review and Commentary/@comment-7418318-20140825132453/@comment-5268982-20140825133022

Yeah, C is in larde quantities inside the body, but maybe it has to exceed certain limits in order for Gajeel to be able to transform his skin..? I dunno man, maybe using science to explain FT is not the right aproach. It's fun though :P

Well, maybe Elfman or Cana could have the last fight. Or Yukino, because I bet she'll join the Tartarus fight too to reunite with her sister. What I think will happen though is that Natsu will wake up and finish his fight.