GrayxLucy
There aren't nearly enough fanfics of my favourite straight pairing, so I decided to write one :) I started to love this pair after the episode where Lucy's dad stalks her for money and Gray follows her to make sure she's safe. i just thought he was so cute when Natsu caught him :)

"It's way too hot to keep walking like this guys, how much further can it be?" Lucy moaned into the humid air, fed up of the heat and the endless walking. It was almost nighttime, the low sun casting a red glow over the five travellers but it was a still, hot day and the heat was making them lethargic.
"Magnolia is just over *yawn* that ridge there, we should *yawn*- should be there in no time." Erza's voice was firm but her feet were dragging on the ground and she could barely keep her eyes open.
"What? Are you kidding me? That's miles away, it'll take us all night!" Even Natsu, who seemed to have an inexhaustible supply of energy (at least, when they weren't travelling in a vehicle) had had enough. "Aye sir." Happy replied drowsily, wings drooping.
"Well if somebody hadn't destroyed half the town we were supposed to be helping, we wouldn't have spent most the day cleaning up and would be home by now."
"Why didn't we just get a wagon home?"
"You wanted to save money Lucy because of the fee they took out of our reward for Natsu breaking everything. And also as soon as you suggested it Natsu started dragging all of us out onto the road because he didn't want to get motion sick yet again."
"Can't we please stop for the night guys? This heat is killing me."
"Erza, there's nothing we need to hurry back for. We may as well camp out here, it's not like we'll need tents or sleeping bags to keep warm."

Gray was the worst affected by the heat, and he kept having to form thin layers of ice over his skin to cool down, leaving him with little magic energy as well as the fatigue caused by a long day of walking. As soon as Erza nodded, he flopped onto the warm ground, encasing his body in yet another ice layer in the hope of cooling down.

The other wizards began to make camp, laying down spare clothes to lie on in a clearing just off the road and stretching a tarpaulin Erza had secreted somewhere in her mountain of luggage between the trees to provide some cover. They all knew it was difficult for Gray to function properly in this weather, so they left him alone to cool down as they prepared food (Natsu did occasionally mutter things under his breath).

Lucy, noticing that Gray's ice layer had almost melted, walked to a nearby stream to get some water, filling her bottle and then offering it to him as he sat up, ice water dripping off his bare skin. To keep cool, Gray had spent the entire mission in just his underwear- Natsu kept taunting him because he hadn't even thought to bring any other clothes. Lucy secretly enjoyed the sight, peering at him from underneath her eyelashes as Gray gulped down the water, already missing his ice.

"Thanks." Gray said abruptly, avioding meeting Lucy's eyes as they walked back to the maekshift camp together. He had been oddly distant with her lately- Lucy assumed it was just the heat putting him in a bad mood, but perhaps it was something else? Lucy hated to think that there was something bothering him, or that she'd upset him somehow. She studied his back, eyes lingering on tautly muscled skin and the smooth curve of his neck and spine. She had just opened her mouth to ask if he was okay when- thud. Eyes on Gray instead of the path Lucy had tripped over a tree root, reaching forwards and taking Gray down with her.

"Owwww... that hurt. Are you okay? Wait, your skin is freezing cold!" Lucy opened her eyes to find herself lying atop Gray who was face down on the dirt, straddling his back. He raised himself off the ground to answer, tipping Lucy backwards. "Yeah, I'm fine, what about-" Gray had turned to look at Lucy, and found himself faced with a view of his dishevelled teammate spread out before him, legs apart and displaying lacy underwear which left little to the imagination. He immediately blushed deeply and tried to look away, but found his eyes were drawn to it, even though he knew Lucy was watching him. He prepared for her typical vengeful kick and yell, but none came. Instead, Lucy blushed as deeply as him and yanked down her short skirt.

They returned to the other two in silence, each too embarrased to speak.
"What took you guys so long, Erza made me wait until you guys got back before I could eat. I'm so hungryyy." Natsu proved a good distraction and the group continued to joke and bicker like always until they finished their meal. The long day began to take effect on all of them and soon they were preparing for sleep. Despite their tiredness, the suffocating heat still made it difficult to get to sleep- at least, for everyone but Natsu.

Listening to his snores, Lucy moaned into the still air "How can he get to sleep so easily when it's this hot?"
"He's a dragonslayer who uses fire magic- he's used to his body being much hotter than this Lucy." Came Erza's steady reply. An idea suddenly occured to Lucy, and she spoke without thinking of the possible consequences.
"Wait, Gray, when I fell on you earlier your skin was freezing cold. Couldn't we sleep close to you and stay cool?" Ohmygod I'd get to sleep right next to him... Wait, did I just think 'get to' sleep next to Gray? Thought Lucy.
"No way, I'm not a freaking icecube!"
"Aww come on. You use Natsu as a radiator to dry off all the time."
"...Fine. But not too close, or I'll start overheating." Or I'll get a little overexcited because you're lying right next to me, Gray added in his head.
Erza and Lucy both stumbled over to where Gray was lying and curled up next to him, relishing in the cool air streaming from his body. All three were soon asleep, worn out by their mission.