Kirk entered his cabin and went straight into the shower to freshen up and brush his teeth. Nausea free sounded great after the morning he had, so after he cleaned himself up, he was planning on going back to bed for a much-needed nap. Unfortunately, his body disagreed and he still felt uncomfortable so he struggled to fall asleep. Knowing he already had drugs in his system to treat the nausea, he didn't consider the need to get any supplies or even get out of bed, opting instead to just keep attempting to find a comfortable position to ride it out.

After nearly 10 minutes he decided he was seriously at risk of ruining his bed, so he made his way into the bathroom just in time to be painfully sick for the third time. After a few minutes he felt better enough to clean up after himself and go back to bed. Kirk was feeling miserable despite the medication McCoy gave him earlier. Now his head was spinning, his whole body felt hollow, and he was freezing. He wrapped himself as tight as he could in his blankets and decided he would comm Bones as soon as he felt warm enough to move and grab his communicator. He hadn't planned on passing out before he could do that though.

…

McCoy planned on stopping by to check on Jim at the end of his shift but a lull in duties gave him an opportunity to have a closer look at the captain's scan and the virus. What he found had him changing plans and going to do a house call earlier than scheduled. This was no mild variant of the virus that the scanner detected, Kirk had somehow contracted a 'mutated' version and could likely be in for a very rough time.
McCoy knew he was allowed entry to Jim's quarters whenever he felt like it, they both had an open-door policy for each other, but this being an official call as CMO he buzzed and waited for a response. When none came, he felt a wave of anxiety and let himself in. Jim was bundled up in the blankets on the bed seemingly fast asleep.

He approached carefully, knowing that Jim was someone you had to wake with caution as it was not uncommon for him to wake up on the defensive. Bones learned quickly at the academy that his friend had some concerning sleep issues. He would survive off very little sleep until he crashed hard and was forced to give into exhaustion.

The kid rarely slept deeply, he was always on alert but when he felt comfortable and safe he would let his guard down enough to get a decent sleep. This was usually when McCoy stayed up late studying or watching something Kirk had no interest in, so Kirk would fall asleep knowing McCoy was awake to 'watch his back'. Once McCoy realized this he kept a close eye on his friend and when Kirks strenuous study load started to get too much for him Bones would purposefully pull an all-night study session so his friend could rest.
The other concerning thing McCoy learned was that the only safe way to wake the kid (without the risk of getting hurt in the process) was to call his name while shaking his foot. Seriously the kid needed to come with his own instruction manual – but McCoy was well certified in both physical and mental trauma, so he learned what worked for Jim and happily adapted. Whatever the kid had been through was not his business, but he could sure as hell figure out how to look after him.

"Jim" having found a foot amongst the pile of blankets he gave it a good shake and sure enough Jim stirred but he was undeniably sluggish
"Jim its McCoy – I need to take another look at ya" Jim lifted his head and looked at McCoy with a confused look as he looked around and found his comm still on the table
"I was gonna comm you but I forgot to grab my comm on my way back…" Jim mumbled as he scrubbed a hand over his face to wake himself up a bit
"Back from where?" Bones asked confused as he opened up his tricorder and started to scan Jim who was still happy tucked up in his cocoon
"bathroom. Threw up again and I feel like crap. I was gonna comm you but forgot to grab my comm unit off the table before came back to bed"

"Jim you've got a fever of 39.4*C (103*F) and you're got signs of dehydration" McCoy scowled as he got up and grabbed a glass of water and handed it to Jim
"Drink this. I'm going to give you something to help with the fever and the headache, but I need you out of the blankets – you can have a sheet and a lightweight blanket but no cocoon"
Jim was obediently sipping his water but stopped when he was told he had to relinquish his blanket.
"I know you feel cold but your cooking kid, come on" Bones carefully unwrapped the heavy top blanket from around Jim and pulled it back to the end of the bed, leaving Jim tangled in just a light blanket and a top sheet so his body's excess heat could vent and help bring down his core temp

Jim was shaking as he sat there with his arms folded over his knees and hung his head
"I know, I know…I'm going to feel like I'm freezing until my temp regulates then I'll feel warm again…. Its just that knowing that doesn't make going through it any easier" he mumbled before he looked up to see McCoy standing there waiting to administer the hypo with an understanding look on his face.
"Yeah, I know" he drawled as he put away the now empty hypo and pulled out his scanner again
"Well they say that a little suffering is good for the soul so try thinking of it as soul food"
"I'd rather not think about food at all right now" his body's shaking was sloshing around the glass of water he just drank in a most unpleasant way

"Fair enough. I do need to increase your hydration though so I'm going to give you an electrolyte solution" McCoy took the empty glass and refiled it with the solution before handing it back to Kirk
"One glass every 4hrs, or you get an IV" he knew the electrolyte solution wasn't the most pleasant taste but with the alternative being a trip to Medbay for an IV it was good motivation to just drink it. Jim could be a real pain when he wanted to be, but he rarely gave McCoy a hard time when he was under the weather. The kid probably just appreciated someone looking after him.

To his credit Jim silently got through half the glass before his still shaking body started to ache too much and he just wanted to lie down, so he downed the last half in one gulp and got comfy.

McCoy removed the glass and scanned Jim again "38.9*C (102*F) degrees, coming down slowly" he encouraged, although he secretly had hoped that it would be better than that by now.
Jim softly puffed out a breath as he groaned and turned his face into the pillow.
There wasn't much more McCoy could do so he sat in a nearby chair to keep an eye on his friend. He thought Jim might have fallen asleep again when Jim groaned again and moved to prop himself up on his elbow
"ugh" he muttered as he pressed his palm to his forehead
"You OK Jim?" Jim looked over to Bones and slightly shook his head
"feel sick…"
"I'll get you a different anti-emetic, will you be alright for a minute while I run back to the Medbay?"
"um..sure, let me just, uh…" Jim stood himself up with a little help from McCoy but as soon as he was fully upright his head spun which made him lean down and grab the bed
"Yeah, sure you will" McCoy said sarcastically as he held his friend steady
A moment later the head rush subsided just enough for Jim to charge off to the bathroom again followed closely by a now concerned Dr McCoy who could guess how horrible Kirk must feel going by how violently he was being sick.

"Jim, I have to take you in. You need an IV for fluids, and a stronger anti-emetic…"
"no. no Medbay, please" Jim managed to pant out between heaves
"Oh for the love of…..your issues with medical care insult me" Bones faked offence was betrayed by the completely unphased look on his face as he helped Jim.
"As your CMO I should remind you that my decisions outrank yours, so I have the right to drag you to medical, against your will if necessary. As your friend however, you know I will still do exactly that – but I will let you stay here provided your condition doesn't deteriorate. That means no fever above 38*C (100*F) and drinking the electrolytes and keeping them down!"
"Deal" Jim replied with only a moment's hesitation as he contemplated his ability to hold up his end.
"Alright then. Now, if you think your done for a minute, I'll get you back to bed then go grab some supplies" with a nod from Jim he escorted his friend back to bed, making sure he didn't cocoon himself again, and took Jims temperature again. Holding steady at 38.3*C (101*F) – at least that was an encouraging sign.
"Go Bones, I'll be fine" Jim grumbled as he curled on his side and looked like he was well on the way to falling back to sleep.