Arthur was greeted to complete darkness when he unlocked the door and entered the flat like he'd done dozens of time before.
He pocketed the key Merlin had given him and scrambled for the lightswitch blindly, a niggling sort of worry starting to stir up in him.
It was unusual for Merlin's flat to be so dreary and cheerless and quiet.
Something was definitely off.
"Merlin?" he called, carefully stepping over the mess strewn on the floor.
Arthur checked the kitchen, the bathroom, Merlin's music room with all the instruments he couldn't afford and then finally the bedroom.
There was a big lump of blankets in the middle of the bed, under which resided Arthur's boyfriend hopefully.
There were tufts of dark hair sticking out from the top of the cocoon and Arthur could hear soft sniffles coming from underneath.
Concern flared in Arthur's chest as he sat on the edge of the mattress.
"Merlin... hey, are you feeling okay?" he asked softly, running a tender hand over his head. "You haven't been picking up my calls."
"'M sick," croaked the wrapped bundle, wiggling closer to lift his head a little and rest it on Arthur's lap.
"What's the matter, darling?" Arthur asked, the endearment slipping out unbidden.
He knew Merlin was truly out of it when he didn't even fake protest or gag at it, just hummed blearily —turning around to push his face into Arthur's jumper.
Arthur got a good view of Merlin from this angle and he looked like death warmed up—skin sickly pale, dark shadows under his eyes and lips dry.
Arthur pushed his hair back to feel his forehead and found it burning. "You have a fever."
"Oh, really?" Merlin mumbled sarcastically. "Because the fact that I feel like the inside of Satan's arsehole didn't clue me in on it."
Arthur couldn't help but bark out a laugh, that immediately subsided when chills wracked Merlin's body and his breath hitched.
Arthur's heart spiked with worry. "Christ, Merlin, what have you done to yourself?"
He pushed a gentle hand inside the comforter to rub soothing circles onto Merlin's back and he practically purred under Arthur's touch.
Arthur suppressed a fond smile, so as to not ruin his scolding. "I told you to not work so hard. This thesis and that godawful internship are not worth ruining your health over."
Merlin made a weak objecting noise but seemed to be falling asleep again, his laboured breaths evening out.
Arthur patted him awake, cupping his face. "No, no wait. Have you taken any medicine? When was the last time you ate?"
Merlin made a vague movement that might have been a shrug, his eyes still closed. "Took paracetamol in the morning, don't remember if I ate."
Arthur sighed. "Alright, I'm going to call Gaius to see what needs to be done and then I'm going to make you some vegetable soup, okay?"
That got Merlin to open his eyes, his expression frightened. "You're going to cook?"
Arthur rolled his eyes, shoving a pillow under Merlin's head and tucking the covers tightly around his body. "Oh, shut it. I'm not going to give you food poisoning or anything. I can make a simple bowl of soup, Merlin."
Arthur was lying, of course. He absolutely couldn't do that without inviting disaster.
He was going to dial Gwen as soon as he was out of Merlin's earshot.
Merlin didn't look any more reassured but seemed too tired to object further, choosing to snuggle into the pillow resignedly.
After Arthur informed Gaius of Merlin's temperature and other symptoms, he promised to drop by in the evening and instructed Arthur to keep Merlin hydrated and rested till then.
Gwen got very frantic when she heard Merlin was unwell and said she was going to come to his aid immediately, until she realised she was in Germany at the moment.
She grumbled for a few minutes, before settling for just providing Arthur with her veggie soup recipe. To Arthur's extreme alarm, she threatened to cut off his balls if he didn't give her hourly updates on Merlin and he wisely chose that moment to bid her goodbye and end the call.
Feeling determined and inspired, Arthur made his way to the kitchen.
In an impressive show of culinary incompetence, he gave up in ten minutes—instead grabbing his coat and quickly going down to the shops to buy a packet of Knorr's.
Arthur prepared a bowl, adding some croutons in the soup after finding a shocking number of bags of them in one of the kitchen cabinets, and opened the door to Merlin's bedroom.
Arthur nearly dropped the bowl.
Merlin was propped up on two pillows, fingers hazily flying across the keyboard of his laptop, looking like he was two seconds from passing out.
"Hey!" Arthur exclaimed, rushing forward to place the soup on the bedside table and snatching Merlin's laptop away. "None of that! You're under orders to rest."
Merlin gaped at him, as though Arthur was inflicting some great injustice on him. "This paper is due tonight, Arthur! You know what Kilgharrah is like."
"You're unwell," Arthur insisted calmly, keeping the laptop far out of Merlin's reach. "I'll email Kilgharrah on your behalf."
Merlin glared at him, crossing his arms defiantly. He was wearing Arthur's faded, long-sleeved t-shirt that looked much better on him anyway and Arthur wondered for the hundredth time why they weren't living together already.
"I'm not six and you're not my mum," Merlin said scathingly.
"Yes, because you actually listen to your mum," Arthur replied, mirroring him. "Speaking of, should I ring her?"
Merlin's eyes widened and he sat back hastily. "No, no it's fine," he said in a rush. "I'll rest and eat your terrible soup, all right? Don't worry her unnecessarily."
Arthur nodded, not being able to help a self-satisfied grin. "Good."
He sat on the bed near Merlin, picking up the bowl of soup.
"What, are you going to feed it to me?" Merlin asked suspiciously, looking uncertain about whether he liked that idea or not.
Arthur snorted, handing him the bowl. "That's a three year relationship privilege. It's only been two."
"Poor me," Merlin muttered, staring into the bowl dubiously. He hesitantly brought the spoon to his lips, and a pleasantly surprised expression came over his face.
"That's not bad," he commented, shovelling more spoonfulls into his mouth. "However, if you wanted soup mix, there was one in my kitchen cupboard. You didn't have to go all the way to the shop."
Arthur flushed, embarrassed at being caught. "Shut up."
Merlin flashed him a smug smile and Arthur was pleased to see that he already seemed to be feeling better.
After the soup was finished and Merlin was drowsy again, he started complaining about feeling 'insanely fucking cold'. The chattering of his teeth was enough evidence for Arthur.
Arthur sighed, removing his jumper and pants and changing into one of the worn t-shirts he had at Merlin's place. He got under the covers, reaching out to hold Merlin, when Merlin wriggled back in the sheets.
"No, absolutely not," he protested. "I don't want to give you whatever virus I've caught."
Arthur smiled. "I haven't had a flu in probably a decade, Merlin."
Merlin seemed vaguely reassured but cautioned for good measure, "Don't kiss me."
"I won't," Arthur promised. But then he did. Right on the tip of Merlin's bright red nose.
Merlin wrinkled it, scowling—though there was no mistaking the twin spots of colour blooming on his cheeks. "I'm just looking out for you, prat."
"Don't worry, I'm the epitome of good health," Arthur assured him.
Merlin huffed, bedgrudgingly allowing Arthur to finally pull him close. "Only you would brag about your health in front of an ill person."
Arthur chuckled, wrapping an arm around Merlin's waist so his face was nestled snugly under Arthur's chin.
Merlin shoved his feet in between Arthur's and hissed suddenly.
"What?" Arthur enquired, absently running a hand up and down his back.
"You're like a bloody furnace usually but when I need your warmth, your body decides to be cold," Merlin grumbled, his voice muffled.
Arthur frowned. "Give me time, it's freezing outside."
However, despite his complaints and protests, Merlin still latched on to him—resting his head on Arthur's chest in the possessive manner that Arthur loved and tightly clutching him in the middle.
Merlin pressed his lips to Arthur's clothed chest, right over his heart and murmured, "Mine."
Arthur's mouth quirked up in a small smile and he kissed the top of Merlin's head, allowing his eyes to fall shut too.
Merlin was breathing noisily, his nose blocked and limbs restless. Arthur would also probably wake up to find a wet spot of drool on his shirt later.
Merlin was stubborn, sarcastic and could be downright mean when he was in a bad mood, especially when he was sick.
It wasn't some perfect, romantic fairytale moment that made Arthur have the realisation.
Amazingly, it was that instant in time —when Merlin was snoring unattractively and holding him in a truly suffocating grip —that Arthur knew for certain he would never love another person more.