A pair of sisters are in the meadow, the younger redhead standing like she would embrace the sun if she could, and the older blonde sitting a small distance away.

"See, Elsa? The sun isn't bad at all, and..." Anna turns around and stops immediately after seeing her sister's condition. Elsa's skin is tomato red from sunburn, and her nostrils are running snot uncontrollably. She is trembling and doesn't look pleased at all. She sniffs up the snot loudly.
"... Anna... Can we go home now?" Elsa asks miserably. Anna stands, wide eyed.
"Uhm... Yeah. Yeah, we can do that..." Anna shakes her head quickly to get over the shock of the state of her sister. "I mean, wow, what happened?" She rushes to her sister's side and helps her up.

"I... I think-" Elsa begins, but is cut off as she sneezes loudly, "I think it's a reverse cold."
"A... reverse cold?" Anna asks. They begin their way back to the castle as Elsa nods.
"People are normally warm, but I'm normally cold, so too much warmth might make me sick... I used to wonder as a child, but now I..." She sniffs hard, "I guess I know."
"AND I got you sunburned... I should have thought about that at least... I'm sorry Elsa... I promise, I'll get you healthy again, okay?" Anna says, carefully supporting her sister as they walk.
"OOOWW! Not there, Anna!" Elsa shouts as Anna tries to find a good place for her arm.
"Sorry! Sorry! How about there?" Anna asks, moving some.
"... That's better." Elsa smiles gently, almost to herself. At least I'm immune to blushing for the next week or so...she thinks
-
"Eeeeeellllsaaaaaaa~~~" Elsa hears Anna's voice from down the hall nearly a week later. Elsa's sickness has begun to fade, and her sunburn is gone; her skin has returned to its naturally pale shade. She smiles at her open book as she hears footsteps growing louder.
Knock knock knockknock knock
Anna's knock. Elsa shuts her book and looks to the door.
"Come in, Anna." she calls. The door opens, Anna walking in with what smells like chicken soup and dressed in maid's attire. "Anna...?"
"Elsa! You're at the shade where I can tell where you're blushing again! That's good!" Anna grins, a sly glint only in her eye.
"You... why are you wearing that?" Elsa asks, flustered.
"Because if you're well soon, then I might not ever get the chance again! I wanted to try it at least once!" Anna explains. Elsa shakes her head slowly. But that's Anna for you. Always curious, a little odd, kind, caring, cute, and more pretty than people give her credit for... wait, what? "Elsa? Are you feeling better today, or worse, because you look pretty flustered. Are you okay?"
"I-I'm fine. I'm actually feeling really good today." Elsa answers, regaining her composure.
"Great! Anyway, it's lunch time, so I have some warm chicken soup for you." Anna says, bringing the soup over.
"Oh, warm! That's good!" Elsa smirks at her sister.
"HEY! You said it was a REVERSE cold! Warm soup helps normal colds! What was I supposed to think?" Anna retorts, getting a little embarrassed herself now, and Elsa giggles.
God, even her giggles are regal... Anna witnesses Elsa's giggle, the way she gracefully shuts her eyes and barely covers her mouth. Anna bites her lip, blushing a little herself now.
"Anna... It's okay. Really. You had the best intentions. And after learning, you still stuck by your promise." Elsa says while reaching to take the soup. Anna smiles and hands it over slowly.
"Careful. The bowl's hot..." The redhead warns, but as Elsa takes it, a thin layer of ice creeps along the bottom, "... or not." She pauses. She wants to stay, but knows that sticking around to watch her sister eat is a little weird. So she nervously starts letting words flow, with a general point in her head, "So... uh, if you need anything else, just..." she turns her head and cones her hands against her mouth "give me a holler! … Heh heh..." She shuffles a little, "I'll go then... I have... um... stuff that needs doing, and-"
"Anna." Elsa says, smiling, her eyes still on the steaming soup. "Would you like to stay?"
"YES!" Anna blurts a little too eagerly, "I mean, yes, I would... like to stay. Is that weird? I hope that's not weird, because, I wouldn't want you thinking that I'm heh heh weird... But I am though, not normal, I guess, and-"
"Anna." Elsa interrupts her again, this time smiling at her, "It's not weird. I... want you here too."
Anna smiles widely and takes a seat.
As she watches Elsa, she thinks back to when the reverse cold was worse, and she got to see a side of Elsa she hadn't seen before...
-A few days before-

Anna knocks at the door, and walks in briefly afterward, warm soup her her hands.
"Elsa? Are you awake?" She whispers in the the freezing room. Elsa groans from under her covers and rolls over. The top of her silver-blonde mane and her intense blue eyes peer weakly at Anna from over the blankets. Her forehead is still a little too pink.
"I brought you some soup... you can eat it whenever you like." Anna says, coming to the nightstand to set it close to her sister, "Just try not to take too long, okay? It'll get cold fast in here." she turns to leave, still feeling guilty for getting her sister so sick.
"A-Anna..." She hears from Elsa's bed a raspy tone, accompanied by a light cough. "I... need more tissues. But for now, could you stay for a bit? Please?" Anna smiles weakly.
"Of course." she pulls up a seat and sets herself in it.
"Th-thank you..." Elsa says, then dives under her covers as she sneezes, peaking back out in the same manner just after. "I... hate being taken care of, and this room has become suffocating after spending years in it, but... thank you."
"Do you wanna use mine instead?" Anna offers.
"N-no, I," Elsa sniffs hard again, "I don't wanna freeze your room too... there's all kinds of water damage involved and occasionally mold so," her eyes shut as she coughs a spell, "I couldn't... but thank you."
"So then I'll stay. That's why you want me here, right? Because it's only bad when you're alone." Anna states. Elsa looks down, and then nods weakly.
"I'll get your tissues in a bit, okay? But first, I think some company is overdue. Don't you?" Anna smiles at the eyes peeping at her. Elsa nods again.
"Thank you..." she says, as the eyes fall shut and her breathing becomes more rhythmic.