A/N: This is my first attempt at writing something like this so I hope it meets your expectations. :)
Warning: This will get pretty adult in later chapters.
Gray wrapped his arms around the dragon slayer's waist, wrapping him in a lazy hug. Natsu was making breakfast, bacon and eggs, the only thing he could seem to manage without burning. A soft yawn came from behind him and Lucy pecked him on the cheek. He watched her hips move as she walked over to the coffee pot and poured herself a cup.
He wasn't sure exactly how it had happened, but he was happy that it did. It was in the summer when Natsu was most in his element. Gray and Natsu had spent the entirety of the afternoon fighting while Happy was off trying to woo Carla. Once they'd finished beating each other to a pulp, they went out for a couple of beers.
The next morning he woke up to find the dragon slayer in bed beside him, snoring more loudly than any normal person possibly could. But somehow it felt right, the flame brain by his side. Natsu and Gray were first, even if the rest of the guild was unaware.
Lucy came later, although not by much. The thought of poly armory had never entered the mind of either of the boys, at least not until that night.
Gray came home late from a mission after being gone for a week or so, only to find Natsu wasn't at his house as he so often was, and he wasn't at the shack he shared with Happy. The only logical explanation had to be Lucy's. Sure enough, there he was, crashed out on her bed with no sign of the blonde in sight.
If had been any other night Gray would have thought better of it, but he was far to exhausted to care. He climbed into bed beside the fire Mage and passed out before his head hit the pillow. On the rare occasion Natsu didn't snore, he was much easier to sleep next to.
"What are you doing in my bed?" Lucy demanded, flipping the light switch and waking both of the boys.
"Oh shit." Gray mumbled under his breath.
"Hey Luce." Natsu smiled, offering her a sleepy grin.
"Why are you both in my bed?" She stomped. "Gray! Why are you naked in my bed!?"
"Sorry, I came home from a mission and I couldn't find Natsu so I came here. By the time I got here I was so exhausted I didn't really thing about it."
"But why were you looking for-" Her eyes widened in realization as she noticed just how close the two boys were to each other. "Oh. Oh. In my bed!?"
"It's not like that Luce." He paused, offering Gray a devilish smile. "Not yet anyway."
"Natsu!" The ice Mage elbowed him in the ribs. He pulled back the comforter and revealed he was still dressed from the waist down. "See, innocent."
She took a deep breath. "So, you two are a thing now?"
"Kinda?" Natsu asked sheepishly, reaching his arm around to scratch in between his shoulders.
"Sorry Lucy. I'll drag firebreath back to my place and get him out of your hair."
"Just go back to sleep." She sighed, rubbing her temples. "I'll go sleep on the couch."
"Aw, Luce. We can't kick you out of your own bed." He scooted all the way over to the wall. "Climb on in. You can sleep between me and Gray so there won't be no funny business."
"Natsu, you're an idiot." Gray mumbled, his face reddening ever so slightly. It was evident Lucy had always had a thing for Natsu and Gray had always had a little thing for Lucy, not that he would ever cheat on Natsu.
"Actually that sounds good." Lucy said, awkwardly climbing over Gray and settling herself between the two. The faintest scent of stale alcohol hit him.
"Have you been drinking?"
"A bit." She mumbled, burying into Natsu's chest. A pang of jealousy rang through him, but he wasn't sure who it was for. The ice Mage knew he should probably get up and move, but he was far too exhausted.
He had no idea how far that one choice would take him.
"Gray, do you want some coffee?" Lucy asked, bringing him back to the present.
The ice Mage released his hold on the dragon slayer and grabbed his cup off of the table. It was already his third cup of the day but it couldn't be helped. Lucy and Natsu insisted on him staying up late every night but he was always an early riser.
"Happy will be back in three days." Natsu said, moving the bacon onto a paper plate. All of the exceeds had been called off on a special mission that had taken nearly a month. The three had managed to keep their arrangement quiet, but once Happy got back it wouldn't be an option. Even with the best of intentions, the cat had a blabber mouth.
"Are you ready for this?" Gray said, asking himself as much as he was the other two.
"I think everything will be fine." Lucy said, although her voice suggested she believed otherwise. She had only been a participant in their arrangement for a couple weeks. Despite the newness of the relationship, Gray dreaded the possibility of it ending.
Past the first few nights of initial awkwardness, everything seemed natural, like it was meant to be. They had all spent enough time together on missions they knew exactly how to be around each other, even if things hadn't gotten too serious yet.
Gray could only hope things would get the chance to get serious.
"I think we should all spend the night together until Happy comes back." Lucy said, looking down at cup in her hands.
"Like we have been?" Gray asked, nodding to the bedroom. It had been mostly innocent so far, but not entirely. Natsu and Gray had messed around before Lucy came around but they had slowed down considerably since she joined them. The ice mage had been wanting more but he was unsure how to ask.
"Yeah, but we need a bigger bed." Natsu said, already shoveling his mouth with bacon.
"Like at a hotel?"
"Maybe we should take a mission." Natsu shrugged.
"That would give us a little longer together before we have to tell anyone." Gray suggested.
"That sounds like a good idea, just the three of us.."
"Just the three of us." Natsu agreed.