Disclaimer: I do not own Fairy Tail, or any of its associated characters and lore. That right belongs to Hiro Mashima.
[ADD]
Avatar's Dark Dragon
[ADD]
Avatar Mikage Forest Branch, Fiore, X792
Having been found by the Priest Arlock fifteen years prior, Natsu Dragneel had risen through the ranks of Avatar as a force of destruction. Initially, everyone, even Natsu himself, was uncertain what role he was meant to play when Arlock told him that his own search for Zeref led him to the young Dragon Slayer, but in time, the teachings of the Black Wizard left a strong impression on the then seven-year-old boy, who made it his goal to one day train under Zeref himself to better develop his own Magic power.
Unconventional though it was, Natsu's genuine devotion to the Black Arts was what led to Arlock calling him for advice for how to deal with a potential problem.
"Gray Fullbuster?" Natsu didn't need to consider it before answering honestly. "Yeah, with all due respect, Priest, I don't think that stripper actually has any appreciation for Lord Zeref's teachings. The Etherious wiping out his birth family kind of makes it worse. I think he's only here to take us down."
Arlock nodded, even if he lacked a flesh and blood face to make an expression of agreement. "I believe you're quite right, Natsu. Do you suppose that we should end him here and now?"
Natsu thought it over before shaking his head in the negative. "We don't know if he's here on his own or on someone's orders. If he's taken out too soon, we'll might have a problem on our heads."
"Perhaps so." Arlock agreed. "A close eye on him will suffice for now, but if he does anything to immediately compromise our efforts, I'm placing my faith in you to dispose of him."
Natsu smirked fiendishly. "You can count on it."
[ADD]
Later and elsewhere in the abandoned church Avatar had been using, Natsu met up with his comrades in the cult, Briar and Mary, trusting that they would help him with Gray.
"So, Gray may be using us?" Briar bit her lip in frustration. "It's a pity. I rather liked him, faults and all."
Mary showed a similarly disappointed look. "Yeah, if only he weren't so closeminded." She then perked up as she brought Natsu's right arm into her hold. "But at least we still have a literal hunk at our side, right, Briar?"
Briar did the same thing with Natsu's left arm saying flirtatiously. "Assuming he can please both of us, Mary."
Gladly getting the hint, Natsu first brought Briar closer to share a kiss followed by doing the same with Mary. Smirking boldly, he quoted. "Well, let me show you both how I dominate gorgeous women."
[ADD]
I can tell that the last two arcs of Fairy Tail just before we got wind of a sequel manga pretty much introduced characters that didn't get enough spotlight or whatever, but why nobody decided to use anyone from the Avatar cult in a good enough position until now is beyond me. Sure, I gathered that an author or two implied a desire to use them for romance purposes, but I wanted to work on them, so you know. Still, I can't help but notice that sometimes in works like this, there's a duo/trio/whatever that are given a romantic value to the protagonist of said story, such as the Tartaros members Seilah and Kyôka, the three female Shields of Spriggan, and, in the case of One Piece which I'm involved with, Carrot and Wanda of the Minks. None of them are bad, mind you, but has anyone ever worked on a Natsu/Kyôka single pairing before for one example?
Also, now that I think about it, how does anyone think Fairy Tail would develop if Team Natsu as we've seen it in canon wasn't in a Light Guild, but in something different? Like the Rune Knights, the Kingdom of Fiore, and all the antagonist factions native to Earth Land? I know some people like myself mostly explore how Natsu would manage in those situations, but undercover or not, Gray and Gajeel were affiliated with criminals for some time just as FanFictionHunter has considered an idea that has Erza be brainwashed at the Tower of Heaven instead of Jellal. It's something to think over, if nothing else.
Anyway, enjoy the one-shot.