Author's Note:

I don't typically dabble in AUs, but I was inspired by the song used in this story (be my forever by Christina Perri feat. Ed Sheeran), and thought a Modern AU setting definitely fit the tone of the song better than anything in Arendelle. This song is really fitting for these two loveable dorks, and I think it captures their relationship well. Please leave a review on this work once you finish it, and also make sure you check out the cute little ditty that inspired this one-shot. It is awfully catchy! I do not own Frozen, the characters used, or the song referenced. Please read, enjoy, and review!

Kristoff could hear the chirpy little tune as he twisted the key into the lock. Anna must be up already and getting ready for class.

He pushed into their small studio apartment and dropped his shoulder bag on the T.V. tray next to the door. He had just spent a long night driving around and delivering ice. He knew he could catch a few zzzzs before he had to be in his class. Despite how exhausted he was, though, Kristoff couldn't help but grin as he heard the words of the tune float through the apartment.

We're on top of the world, we're on top of the world now darling so don't let go. Can I call you miiiiiine, so can I call you mine now darling for all of time? My heart finally trusts my mind. And I know somehow its right…

Anna's voice, light and wavering, lifted into the foyer area with the tune. Kristoff chuckled. He loved hearing her sing so unabashedly. She was always embarrassed to sing in front of him. She must not have heard him come in if she was still performing.

"Ooooooooh we got time, yeeeeaaah. Darling just say you'll stay, right by my side. Ooooooooh we got love, yeeeeeeah. Darling just swear you'll stand, right by my side."

He walked past the open kitchen, past their "bedroom," (which was sectioned off with a snowflake bed sheet hanging from the ceiling, because, as Anna continued to reminded him, it was winter), and stepped lightly across the worn hardwood floor. Catty-cornered from the open bathroom door, he stopped. Anna was standing in front of the medicine-cabinet mirror, her hairbrush in her hand, which was doubling as a microphone. He could just see her reflection, but he knew that she couldn't see him.

"We're on top of the world, we're on top of the world now darling so don't let go- mmmmm. I've got something to saaaaay, you're perfect, in every way I'm going to shout it out! I wanna tell you now, cuz I know somehow it's right."

Kristoff couldn't keep his eyes off of the reflection of the beautiful woman. She was oblivious to his presence, and continued rocking into her hairbrush. She was still in her pajama shorts and camisole, her hair was loose down her back, and her make-up supplies were left untouched. Anna, his Anna, was perfect. A loving grin settled on his face as he continued to enjoy the impromptu concert.

"Ooooooooh we got time, yeeeeaaah. Darling just say you'll stay, right by my side. Ooooooooh we got love, yeeeeeeah. Darling just swear you'll stand, right by my side! Be my forever, be my forever, be my foreverrrrr. Be my forever, be my forever, be my foreverrrrrr."

Kristoff decided that he couldn't just stand and watch anymore. He moved quietly behind her while she sang the bridge like no one was watching.

"You're the bright blue sky, you're the sun in my eyeeeeees, woooaaaaahhh…"

"Oh baby you're my life, you're the reason whyyyyyyyy…" His golden tenor mingled with her light soprano.

Ann's eyes flashed open and she spun to face him, her cheeks flaming red. "Oh, God, Kristoff, you scared me… how long have you…?"

Kristoff ignored her stuttered speech and moved in front of her. He pulled the hairbrush out of her hand and placed it on the sink behind them. His other palm settled on her waist.

"Wait, what? Kristoff, what…?"

He began to step in time with the music, just left and right, and tried to encourage her to step with him. He raised his eyebrows at her while he continuing to sing.

"We're on top of the world… We're on top of the world now darling so don't let go…"

Anna's high-pitched giggle filled his senses, and she beamed up and stepped in time with him. Her voice finally mixed with his, and they danced and sang together.

"And, oooooooh, we got time, yeaaaaaah we got love. So darling just say you'll stay, right by my siiiiideeee. Oooooooh we got love, yeeeeaaah. So darling just swear you'll stand right by my side. Be my forever, be my forever, be my foreverrrrr. Be my forever, be my forever, be my foreverrrrr."

Anna paused and giggled as Kristoff spun her around his finger and pulled her to him so her back was against his chest. He continued the verse, "Will you love me forever?"

"I'll love you forever," Anna sang in reply as he untwisted their bodies and continued to dance to the beat of the song, "Be my foreverrrrr."

"Be my forever, be my forever, be my foreverrrrrr."

The song faded away, and the two broke apart, laughing and smiling at each other.

"Kristoff, you scared the bejesus out of me! How long had you been standing there, right behind me, watching me sing…" she looked behind her where Kristoff had set her hairbrush, "Watching me sing into my hair brush?" Her hands came up to cover her coloring face. She shook her head and mumbled, "I am so embarrassed. I mean, singing into a hairbrush? How ridiculous must that have looked?"

Kristoff laughed warmly and pulled her into his chest, "It was adorable," he whispered.

She groaned, "Never. Singing. Again."

"Well, I wish you would," Kristoff let her go and moved out of the bathroom, "Because you really do sing well."

She laughed and pushed him out, "Yeah, okay, sure. Now go. You should get some sleep. And I have to finish getting ready for class."

He only resisted a little, though jumped a bit when Anna shut the door behind him. He rolled his eyes as he heard the click of the lock.

Kristoff grinned and moved back into their kitchen. He was in the middle of ransacking the fridge when he heard music start playing, muffled by the door between him and Anna. The sound of her voice quickly floated above the music and Kristoff smiled widely.

He wondered if he knew the words to this song.