Disclaimer: I do not own Fairy Tail, or any of its associated characters and lore. That right belongs to Hiro Mashima.
Legionnaires of Zentopia
Kardia Cathedral, Magnolia Town, Kingdom of Fiore, Ishgar, Earth Land, X791
As Legionnaires of the Zentopia Church, the most influential religion in the Kingdom of Fiore, Mary Hughes, and her partner, Coco, were tasked by the Archbishop himself to awaken Zentopia's strongest weapon in the Kardia Cathedral, one of the three great churches in all of Fiore, in the event catastrophe was approaching all of Earth Land. Entering the Cathedral and heading straight for the lower levels, Mary and Coco soon arrived at the underground altar where they saw the detailed coffin they were meant to open.
Despite her usual tough attitude, the whole situation caused Coco to audibly gulp as she turned to Mary to say. "Is it natural for those given this assignment to worry about awakening an undead monster from its slumber?"
Mary's response was to roll her eyes and scoff. "Don't be so dramatic, Coco. I've done this before, and he's not all that bad." Turning back to the coffin, she added, though. "But I can see the resemblance to those old movies about Vampires and Mummies. In fact, I saw it the first time I did this."
Not exactly cheered up from Mary's words, Coco nonetheless tended to unlock the coffin alongside Mary. Once opened, the two ladies peered inside to see a still pink-haired young man that brought a genuine smile to Mary's slightly sadistic face as Coco couldn't help but comment. "Well, it looks like the corpse is both well-preserved and good-looking."
Mary laughed at her friend's words before then bending down to kiss Zentopia's greatest weapon on the lips. After giving into her kiss for a long moment, Mary turned back to see the man inside wake up at last and exit the coffin on his own two feet. Letting loose a loud yawn, he said to the Command Magic user. "Hey, Mary. You look gorgeous as ever." He then turned to Coco and looked surprised before showing an interested smirk that brought a shiver to the girl's very being.
Gulping again, Coco held out her hand to Mary's apparent love interest as she introduced herself. "It's nice to meet you, Etherious Natsu Dragneel. I'm Coco."
The Etherious merely grinned before enveloping Coco in a tight hug. "Just Natsu is fine, Coco." He then proceeded to kiss a surprised Coco as Mary shook her head at the sight.
Although I don't know if it's exactly feasible, I am kind of interested in a Fairy Tail story that has Natsu/E.N.D. have a similar position to Hellsing Ultimate's Alucard/Dracula. As for pairing him with both Coco and Mary Hughes, it seemed like a good idea since they both have developed enough bodies.