Gajeel's death was a surprise to me. We've discovered Bradman is an Etherious. I kinda expected he wasn't human. What I don't get is why he possesses the abilities of the Nine Demon Gates. After noting his possession of Silver's Devil Slayer Magic, I have a theory Bradman was a human Satan Soul Take Over Mage that became an Etherious after taking over the Nine Demon Gates. It would've been during the 7-year time skip or before the year X781. Sorry if this next part sounds like fan-fiction. He broke into Cube and took over Silver's Ice Devil Slayer Magic first, using the black markings to defend against the Curses of the other eight Gates. Then he took over their Curses and then killed all of them with Silver's Devil Slayer Magic, sending them to Hell's Core to be resurrected. Due to overuse of his Devil Slayer Magic and preforming taking over on to many Etherious, he lost control of the black markings and stopped being human all together. He then ran into Zeref, who, impressed, was observing his movements and offered him to join Alvarez.
That's my theory anyway. That said, my next question is why Mirajane didn't show up to help Gajeel and Levy. Her Take Over would've been extremely useful. If Hiro wanted Fairy Tail to have a happy ending, he could've had Mira Take Over Bradman's Necromancer and keep Gajeel alive. I'm guessing Mira will arrive and ask what happened and where Gajeel is and Levy will berate her for not being present to help. Screaming, demanding to know where she was, shoving, hitting, and sobbing until she falls to her knees in tears, crying and apologizing.
Also, if Mira took over Bradman's Curses and Devil Slayer Magic, she would've been able to go toe-to-toe with E.N.D. when he awakens.
My thoughts away.