(Note: I know Sasuke probably would be too scared to leave Itachi, get off my back!)
First the feeble thumps on the bedroom door, a small muffled voice, and then a pause before the door clicked and swung open. Of course it was unlocked; Sasuke had only failed to realize that as he expected it to be securely locked as usual. The young child gibbered about something, and then began to sob and cry, causing Itachi to groan miserably under his blanket. He was sick; fever, sore throat, hoarse voice, clogged sinuses, and a splitting headache that was made no more bearable due to Sasuke's whining. Itachi wiggled under the sheets a bit further, hoping that Sasuke would up and leave once he noticed that he was being ignored. Sadly, Sasuke only slid to the floor and wailed louder.
Itachi peeked out from his warm linen nest to look at Sasuke with a pleading expression. Please don't make me get up...
"Get up," Sasuke moaned. Itachi felt like moaning as well, if his throat wasn't so sore.
"What d'you want," He answered, barely a whisper.
Sasuke lit up at the minuscule response. He mumbled, "Daddy won't let me go outside 'cause he says somebody has to watch me an' he doesn't want to."
"Go get mom…"
"Mommy's making dinner. Come outside!" Sasuke whined once more, pulling on Itachi's arm.
"I'm sick and I know you've caught it too because of your temperature this morning, neither of us will be going out today." And hopefully tomorrow and the day after that if I'm still sick…
"But Itachiiiiiiii," Sasuke began to lament.
Itachi took Sasuke and held him to his chest. Sasuke sighed, and stretched out, falling asleep sooner than Itachi.
Years later, an eighteen-year-old Itachi lay in bed, fatigue weighing his body down. He had killed the clan and told Sasuke the truth some years ago, convincing the boy to continue training in Konoha and learn under Kakashi's teaching while he continued risking his life for Sasuke and Konoha. He had been cut with a poison-laced kunai earlier and was suffering the side effects of the antidote.
A familiar voice spoke, "Itachi…"
Oh God. Oooohhh God, no, not again…. Itachi sighed deeply after concluding that he wouldn't be spared if he faked death or sleep.
Sasuke prodded Itachi's side, calling his name once more. Itachi was facedown, face buried in his pillow. "No, whatever it is, no," Itachi's muffled voice sounded from the deep, dark depths of his pillow.
"But you said-"
"NO," Itachi slapped Sasuke's arm for emphasis as he tried to poke him once more.
Sasuke slapped his brother in retaliation. Itachi slowly turned to fix Sasuke with a hard stare, moving onto his side. "Am I about to bitch slap you?" he threatened lowly. He normally wouldn't be so quick-tempered, but the illness had drained too much of his patience.
Sasuke returned the stare, poking the fire instead of taking the hint: "Maaaybeee?"
Itachi was about to do it, too, before he remembered how he had defused this kind of argument years before. He hauled Sasuke onto the bed, rolling so that he left Sasuke with no escape between him and the wall. Sasuke squirmed and kicked, protesting, "I can't be sick, I don't get enough water every day- I'll need to get an IV shoved into my arm!" Anyone in the Land of Fire knew Sasuke would either kill a nurse or very nearly kill one to avoid a needle.
Itachi teased, "Ooohhh really?" He mercilessly cuddled Sasuke to his chest and went as far as kissing Sasuke's face. Sasuke shrieked and repeatedly tried to shove Itachi away. "Ah stop it, you're going to make me puke on you," Itachi laughed.
Sasuke stopped squirming and decided to take desperate action. He turned himself over to be face-to-face with his grinning brother, and a trembling lower lip followed by teary eyes followed. Sasuke began to cry. Itachi's grin slid off his face as Sasuke whimpered and sniffled. When his grip loosened, Sasuke sprang up and attempted to dive over Itachi's side. Not willing to give up the fun, Itachi grabbed Sasuke and held him down with his legs. "You're such a little baby!" Itachi hissed.
Sasuke crossed his arms and turned away from Itachi, tearing up somewhat still. "Shut up, I hate you."
"Aw, I made Emo Kid cry for real."
Sasuke rubbed an eye. "Yeah, you did, alright? Quit it… You know I don't like needles…"
Itachi felt a pang of guilt. He wrapped his arms around his little brother. "Okay, I'm sorry. I'm not contagious; I am just having side effects of some medicine I had to take. You'll be fine. You know, you really are a freakin' crybaby…" Sasuke tensed. "… My baby, though," Itachi added, smiling.
Sasuke still refused to be tempted out of his Emo Corner, however. Itachi wasn't about to give up on this either. He snuggled against Sasuke, speaking in a babying voice, "C'mon, baby Sasuke."
Sasuke huffed and growled back, "I don't want to like you, get off me."
"Awwww, you know you like me, you know you wanna hug me."
"Nuh-uh," Sasuke grunted.
Itachi began to tickle his brother, cheering in high squeaky tones, "Sasuke-cutie! Sasuke-honey knows he likes Itachi 'cause Itachi gives him luvvins!"
Sasuke soon began squeaking and shrieking shrilly with laughter, rolling onto the floor with Itachi on him. It was in the middle of Itachi giving a slobbery raspberry on Sasuke's exposed belly that they both looked up to see Kakashi at the open window, chin resting on the back of his hand as he watched the two brothers with interest.
"We're ill," Itachi quickly lied, straightening.
"Really ill," Sasuke agreed.
"Uh-huh…," Kakashi mused, nodding slowly before drumming his fingers against the windowsill and leaving.
Itachi leaned to watch the ninja go, and then pounced on Sasuke, restarting their game, side effects from the antidote washed away by the healing power of the close bond two brothers would forever share.