Another nightmare scenario. Yes, yes, it's been done to death, but I wanted to explore a slightly different take that's based on a popular fan theory. As you read, you'll see what I mean.
Power
Anna jolts awake, screaming Elsa's name as though the queen is being murdered right before her eyes. The light sleep Elsa is in dissolves at the cry. She rolls over so fast she nearly rams into her sister.
"Anna?!"
The princess sits upright, trembling. She stares at Elsa with wide, wet eyes.
Elsa scrambles to a seated position and reaches for her sister's face. She recoils slightly when her fingers come back damp. A cool burst of magic travels through Anna's skin as Elsa's hand brushes sweaty strands of hair from her eyes.
"What's wrong? Are you hurt?"
The labored breaths and tears brimming at Anna's eyelids answer Elsa's frantic questions.
"You had a bad dream," the queen sighs, partially in relief. She opens her arms. "Come here."
Anna's failure to acknowledge her sister rattles Elsa more than she cares to admit.
"Hey," Elsa hopes her voice is reassuring as she strokes her sister's arm. "I'm right here."
The redhead stiffens at the contact. She runs her hands over her face and looks away.
"Anna?"
Usually, when Anna has a nightmare, the first thing she does is seek Elsa's arms. She throws herself into her sister with the force of someone two times her size. Not every bad dream drives the princess to tears, but some leave the queen's nightgown soaked at the shoulder.
What she doesn't usually do is sit in silence, actively avoiding her sister's shoulder to cry on.
"Anna, come here," Elsa tries again, still soft and patient.
"I'm—I'm okay," the princess looks away, but Elsa can already see two teardrops have fallen.
"Sweetheart, you're not okay. Talk to me," the queen pleads, reaching for Anna's hand.
Elsa is both confused and hurt when Anna bats her sister's hand away.
"Anna?"
"I don't wanna hurt you!" the princess cries out, curling herself into a protective ball.
There's a sick feeling in Elsa's stomach at those words. What's worse is they're coming from Anna.
"What are you talking about?" Elsa's hand hovers near her sister's shoulder. "You would never hurt me."
Anna pulls her knees up to her eyes and sobs, rocking herself as she does.
"You're scaring me," Elsa hates to admit this since Anna is so worked up already. "What happened? What was your dream about?"
"Fire. I burned y–you with th–the f–fire," the princess struggles to form words around her cries.
"What fire?"
"My fire!"
It doesn't take long for Elsa to realize what that means.
"You...had a dream you had fire powers?"
Anna nods. Tears dribble down to her chin, mopped by her sleeve.
"I b–burned you alive, a—and I cou–couldn't stop it," she pauses to wipe her runny nose. "I tried, b–but I couldn't m–make it stop."
"Oh, Anna," Elsa inches closer, desperate to offer some measure of comfort. "Hey, c'mon, it's okay. You don't have fire powers, and you don't need them, or any powers. You know why?"
Anna shakes her head 'no' with a few hiccups.
"You're strong enough without them," Elsa dares a light hand to Anna's back, and she's secretly pleased to see the princess hasn't rejected her touch. "Your love is your power. It was stronger than my fear, than anyone's fear, and it always will be."
The queen tests the waters further by placing a cool hand on Anna's arm.
"Look," Elsa entreats. "Nothing bad is happening. There's no fire, Anna."
Anna peeks from behind her knees.
"N–no fire?"
"No fire," Elsa promises, drying the wet lines on Anna's cheeks with her thumbs. "See?"
When she truly believes that it's safe for her older sister, Anna reaches out, winding her arms around Elsa's neck.
"It f–felt so real," she cries against Elsa's throat, taking in heaving breaths between sobs. "Y–you were screaming. Begging m–me t–to stop. I couldn't do an–anything!"
"Shhh," Elsa strokes Anna's hair, holding in her own tears as best she can. "It's over. You're awake now."
"I don–don't wanna ever ha–have that dream again."
"I know, Anna. Try to relax, okay?"
Anna tries and fails to breathe in any way that could be considered normal; it ends up coming out fluttery and erratic. Elsa runs her hand down Anna's back.
"I've got you. Deep breaths," the queen coaxes as she pulls her sister into her lap. "Just breathe for me, okay?"
It's a combination of Elsa's soothing and her cool aura that finally neutralizes Anna's adrenaline rush. She heaves an exhausted sigh, limp in Elsa's arms. Nothing can hurt Anna right now, not even the memories of her nightmare. Once Anna settles down a bit more, Elsa rests her hand over the princess' eyes.
"What are you doing?"
"It'll help with the swelling," Elsa explains, gently tracing Anna's eyelids in slow, predictable patterns. "This should feel a little better, at least."
Anna sits up to place a shy kiss to Elsa's cheek.
"What's that for?" Elsa laughs in that warm, kind way she's reserved just for Anna.
"Just being here," Anna snuffles. "Just...thank you, Elsa."
The queen nods with a grin, gliding her thumb along Anna's cheekbone. She's taken aback by just how hot Anna's skin is. It's always warm, but after her bout of tears, it's almost burning. She brings the back of her hand beside Anna's throat, checking for a fever.
"You're kind of warm. Do you feel okay?"
"Yeah," Anna rubs at her eyes. "I'm okay."
Elsa opens her hand. A few icy crystals twirl from it and dance through the air in a brilliant show of soft blue light. Each crystal chimes a slightly different note when it's curiously poked by the princess. Anna creates a miniature symphony, the radiance of the crystals emphasizes the glow in her eyes. Elsa can't help but press a soft kiss to Anna's forehead when she looks back at her with a smile that could thaw a glacier.
Like Anna, Elsa has access to a power that is unseen, but felt. The light show certainly doesn't hurt, though.
Closing notes: So there's theories that Anna may have dormant fire powers or had them at some point. I'm not in love with the idea because I like the fact that Anna is 'ordinary' at first glance. We all know how wonderful of a character she is because of her personality traits, which in itself, is a kind of power. Her love is so deep and powerful, she could thaw her own heart. Not even Elsa's own parents could get through to her, it was Anna who broke down the walls Elsa built.
So, Elsa essentially made an ice xylophone because...I felt like it. She can make ice clothes, why not musical ice crystals? The feasibility is questionable, but so are ice powers to begin with.
