Who's ready for a rematch? Natsu stops Gray as he's about to sacrifice himself, and he thinks it over a bit. In the end Lyon could just have been resurrected again using the Moon Drip (he has allies, he reveals), so that would have amounted to nothing. Instead, it's time for the decisive battle...
Time for a flashback into Gray's past.
Back then, Deriora ran rampant. But let's start at the beginning...
With a little help from Happy, Lucy made it back to the village and is preparing a trap for the arriving enemies. Oh btw, before Natsu revealed himself last episode, the foes said they were going to destroy the village. That's why she's there.
Natsu decides to take on an S-Rank mission. Only three people in Fairy Tail are allowed such high-ranked (in other words - dangerous) missions, and he's not one of them. The ones who are allowed are Erza, Mistogan & Laxus. There's a second floor in the guild house, to which only these three (along with the master, of course) are allowed. Happy flies away with the least dangerous of the current three S-Rank missions, a visit to a cursed island, to cure the island of its curse.
Natsu manages to trick Lucy into going with him. They reach the harbor yet no one is willing to take them along. That's when Gray shows up, sent by the master to bring them back, so Natsu knocks him down and off they go. Oh, they did find someone willing to take them to the island, finally!
