I am not sure whether someone here in this wiki had already made a blog about this or maybe I'm the first to do so but then again who am I kidding?
Anyways, this blog is about God Serena who had debuted in the Alvarez Empire arc as the First God of Isghar and the most powerful Mage of the continent who had defected to the Alvarez Empire and joined the Spriggan 12 under Emperor Spriggan aka Zeref according to Hyberion, the Second God of Isghar.
From the looks of God Serena, he looks way too suspiciously like Yury Dreyar, one of Fairy Tail (Guild)'s founding members (Mavis Vermilion, Precht Gaebolg and Warrod Sequen) who appears to be on a very, very bad mood written all over his face for some reason if I'm not wrong.
My theory is that he might actually be Yury Dreyar who had somehow managed to keep his charming good looks for a over hundred years unlike Warrod, a tree old dude, probably used the incomplete version of Fairy Law that kept Mavis from even aging or growing up.
In Fairy Tail Zero, Yury told Zera that he will protect Mavis with his life when the illusion ghost asks him before disappearing in acknowledgement that she's nothing more than an illusion Mavis had unconsciously created all along and he, Precht and Warrod had to play along until he called her out on it.
At the end of Fairy Tail Zero, it is said that Yury died in old age after getting married and had his son Makarov Dreyar at some point in the timeline but probably he actually didn't and made it look like he died.
So I can guess he defected to the Western Continent in an infiltration mission to delay them from taking Fairy Heart or destroying the empire from the inside to prevent Alvarez from attacking Isghar to protect Mavis probably known only to his fellow Gods of Isghar to keep it a top secret from their other fellow Wizard Saints.
Or if he's not Yury at all since he's deceased and God Serena is a completely different character introduced into the arc, maybe God Serena has his own reasons why would he defect to Alvarez which was ruled by the most powerful Dark Mage of all in history, Zeref himself.
Feel free to comment your own opinions and theories about God Serena.
Sorry again. I really suck at editing. Blogging may be my thing I do best. :D