Chapter 499 of "Fairy Tail" gave us a heartbreaking scene where Gray and Juvia were forced to battle each other until one of them dies. To break the spell, the two committed suicide but Juvia was able to cast a spell on Gray which kept him alive.
In the next chapter, we followed through the revenge of Gray on Invel for the supposed death of Juvia. But apparently, Juvia was still alive and was healed by Wendy. Not knowing about Juvia being alive, Gray battled Invel but before Invel was defeated, he revealed to Gray that Natsu in fact, is END (Etherius Natsu Dragneel).
"Fairy Tail" Chapter 501 Spoilers
Fans theorized that Invel is still alive and not been defeated. Gray, on the other hand, had lost his fighting spirit and could no longer fight Invel. Wendy will then volunteer and will be insulted by Invel. She will release her Dragon Slayer magic and ultimately defeat Invel.
Brandish's magic did not seem to have that much of an effect on Neinhart but Natsu still attacked him. Some fans believe that God Serena will still be alive as long as Neinhart is, and Natsu is trying his best to take him down fast.
Rumors regarding the real relationship between Eileen and Ezra has been around for a while. Some say they are sisters but others say they must be mother and daughter. In a previous chapter, it was revealed that Eileen has a scar on her belly. It was not explained how she got it but there are theories that it is unlikely from childbirth but it can be from an attempt to kill her and the child inside her womb.
Gray will have to eventually battle with Natsu but most likely not in the next chapter. "Fairy Tail" chapter 501 is titled "Mari and Randi" and it will be a huge fight between Dimaria and Brandish about Randi's betrayal of the Alvarez Empire.
Fans will have to wait for the next chapter to come up to see if the predictions are right.