Disclaimer: I do not own Fairy Tail, or any of its associated characters and lore. That right belongs to Hiro Mashima.
Steaming Phantom Dragon
Hargeon Town, Fiore, Ishgar, Earth Land, July 2, X784
When Phantom Lord members Natsu Dragneel, Happy, and Juvia Lockser arrived in town, they were quickly led to a sight that quickly disgusted them. Not only was Bora using illegal magic to sweep a large group of women off their feet, but he was doing it while under Natsu's own callsign of Salamander. Natsu had half a mind to deal with the scumbag on his own, but a quick look from Juvia warned him that she wanted to deal with her ex-boyfriend on her own. Transforming her hand into a whip of water, Juvia let it loose on Bora's face once she was within striking distance.
With his concentration on charming the women broken, Bora was not amused. "Hey, what's the big idea?!" Turning to the source, he was then shocked to see who it was. "Juvia?!"
"Juvia would like to know why you were using illegal Charm Magic on these girls, Bora." She said uncompromisingly.
Bora looked scared in the face of all the angry looks everyone was giving him. "Would you believe me if I said I was recruiting ladies for a model gig?" He asked sheepishly before following his line with. "In Bosco?"
Before any of the girls could attack him for apparently being in the slave trade, another Water Crane hit Bora in the face into unconsciousness. Turning back to the source, Juvia saw that it was Natsu who did the deed.
"To be fair, you were the one who taught me your magic, after all, so I guess you did deal with him all together." Natsu shrugged at Juvia's gaze.
"Aye, that makes sense." Happy commented.
Juvia giggled. "Well, no harm done then." Turning to the crowd surrounding them, she then asked. "Can someone please get the Rune Knights here while Juvia and her party keep an eye on Bora?"
Seeing someone about to do that, Natsu's attention was soon taken by a nearby blonde who tapped him on the shoulder.
"Thanks for helping us." She said kindly before she started to pity herself. "I'm just disappointed that I didn't recognize what he was doing in time." She then sighed. "And I call myself a mage."
Natsu then smiled. "Oh, you're a mage?" Seeing her nod, he then said. "You're more than welcome to join Phantom Lord, if you're not with a guild already."
"Uh, really?" She said surprised before looking excited when Natsu nodded. "Well, I could use money and a place to stay, so, how about I come with you to there before deciding?"
"You'll go with Natsu?" Juvia asked in an almost threatening tone of voice which scared the blonde and forced Natsu to act.
"Easy there, Juvia! I was just asking if she'd like to join our guild!" With a grin, Natsu then brought Juvia to him for a kiss that stunned the blonde with the intimacy of the kiss and exasperated Happy due to having already seen something similar before. Releasing her lips, Natsu then told Juvia. "And I would never cheat on you with anyone."
Juvia giggled happily with a blush before turning to the blonde with a sincere smile and a curtsy. "Juvia Lockser of Phantom Lord's Element 4 team." She then gestured to her companions. "This is Juvia's boyfriend, Natsu Dragneel, and his sidekick Happy."
"Can I really be called a sidekick, Natsu?" Happy asked downcast only to be happy again when Natsu gave him a fish.
The blonde eventually smiled again. "My name is Lucy." She then noticed their eyes widen for some reason. "Is there something wrong?"
Natsu was quick to offer an explanation. "Uh, no, I just remembered that Master Jose wants us back soon."
"Best not to keep him waiting." Juvia commented with a nod.
"Aye!" Saluted Happy.
As soon as the Rune Knights arrived and were informed of what happened, Lucy worked with them and the three members of Phantom Lord to deal with Bora's gang before the four could leave for the guild headquarters. On their way there, Natsu, Juvia, and Happy shared a hushed conversation which Lucy politely decided not to overhear.
"You guys don't think that Lucy is the Lucy we're supposed to be after?" Happy asked.
"How should we tell her?" Juvia inputted.
"We're going to have to do it gently, but still offer her membership." Natsu said to his friends. "From what I understand, her dad's having money problems. If Lucy joins Phantom Lord and we make a mutually beneficial deal with her dad, everybody could be potentially happy." He then added. "I hope."
I think I did good with my first Fairy Tail one-shot. There should be more stories of Natsu joining a different guild other than Fairy Tail, especially if the pairings make sense. No offense to FFN's Natsu is Awesome, but if you're going to make a challenge story about Natsu being in Phantom Lord, it would probably make more sense if Juvia is a romance option for him. Anyway, I've been thinking of maybe expanding my one-shot/challenge reach into Magi, Seven Deadly Sins, Black Clover, and maybe Robotech among others, but I'll wait to see more of each before making my decision.