User blog comment:IamJakuhoRaikoben/Chapter 374: Revolution, Review./@comment-4489126-20140307182048/@comment-7418318-20140308092024

If that was the case I think Natsu wouldn't be acting like that.

As for how Franmalth could have gotten Hades' soul, I've come up with four theories so far:
 * 1) Hades traded away his soul to Tartarus to get his Demon Heart and was already soulless or missing part of his soul when he fought on Tenrou (which would explain why he turned from good to totally evil.
 * 2) Hades traded away his soul to Tartarus to get his Demon Heart. As a result his soul was bound to Franmalth and upon his death, instead of going to the afterlife, went into the Demon's "arsenal".
 * 3) Zeref killed Hades by ripping his soul out of his body and Franmalth had access to the place it was kept at.
 * 4) After his physical death, Hades lingered on in the living world like Mavis and Roubaul. At some point he crossed path with Franmalth and got eaten.