Ace offered to take first watch that night, and while the Strawhats clamored to insist he sleep, being their guest and all, he smiled and reasoned that with his Devil's Fruit ability, he wouldn't get cold as easily as the rest of them would.
"Well," Sanji said dubiously, "if you're sure. Wake me in a few hours and I'll spot you."
The freckled pirate tipped his hat with a grin, and Luffy poked his head up from the other side of the campfire, where he'd been rolling around with Usopp. "Ara? Ace, you're going to take first watch?"
"Yeah, it's no problem."
"Then I'll stay up with you!" Luffy said excitedly, hopping up onto his feet. "It's okay right?"
And the rest of the crew bit back smiles when Ace's expression softened, and the older pirate replied, "Of course it's okay, Luffy. Come and get comfortable, we gotta be quiet so these guys can go to sleep."
Luffy rushed to obey with an alacrity that not even Nami or Zoro could inspire, and settled quickly at Ace's side; Vivi said, "Oh, Luffy, you'll get cold," and Nami rustled around their packs for a blanket, but Ace slung an arm around their captain's shoulders and hauled him close.
"No he won't," the Whitebeard pirate promised, and Luffy giggled suddenly, wrapping his arms around his brother's waist.
"Remember back in Goa, when it got reaaally cold at night and we stole all Dadan's blankets to make a fort?"
Ace hushed him, pulling him a little closer, but he was grinning, too. "She wasn't too happy about that in the morning."
Luffy's eyes were wide and bright when he peered up at him. "But we were warm!"
The Strawhats settled in for the night, comfortable despite the chill and content despite the sprawling vastness of the desert all around them, because above the quiet crackle of the fire they could just make out the low, steady thrum of hushed conversation; whispered stories and muffled laughter, as the reunited D. brothers caught each other up on the last three years.
Sleep found them with smiles on their faces, and a warmth in their chests that had nothing to do with the campfire.
Sanji woke up on his own a few hours later, out of habit; he sat up groggily, rubbing his face, and glanced across the small campsite. Ace hadn't woken him, but a part of Sanji had figured he was probably too polite to in the first place. He was about to get the man's attention, but he stopped himself just in time.
Sanji's dear, wild, whirlwind-of-a-boy captain had nodded off at some point in the night, curled up a little against the wind, fast asleep with his head pillowed comfortably on his brother's lap; looking much more like an overgrown kid than Sanji had ever seen him, and perfectly at peace with the world.
And Ace was carding fingers through his little brother's hair, in a gesture that looked doting and habitual, with that smile on his face that Sanji knew all too well. He'd seen it before, on Nami's face when Arlong Park fell, and on Chopper's, through snow and tears and the ringing echo of an invitation;
Half elation, half wonder-
How could I possibly deserve you?
"He's a little slow," Ace said suddenly, voice fond and soft, and Sanji knew better than to think Ace hadn't noticed the moment he woke up. "And he doesn't always think things through. But he's yours, once you have him, and he'll give you absolutely everything." The Whitebeard pirate lifted his eyes, and they were dark and burning and fierce, but not at all unfriendly.
Sanji knew that look from Zoro, when the swordsman would step seamlessly to Luffy's side like it was his birthright. Knew it from Usopp, when Luffy fell asleep on his shoulder with all the trust in the world.
So the cook inclined his head, smiled at the fire, and said, "We're just starting to figure that out."