A/N: Hello there! So this is my first Frozen & Rise of the Guardians fanfic, I'm just so in love with the idea of Elsa & Jack Frost that I had to write something for them. I just wanted to write a simple story about Anna making sure that her sister gets a happy ending too which is why technically Jack Frost is human for this story. I hope you guys like it, and sorry for the short prologue but I promise the chapters will be longer! I just wanted a short little intro into how Jack fits into this story. P.S. Thank you HoplessRomantic183 for catching those tiny detail mistakes I made, they're all fixed up now!

Prologue: Formal Invitations

Anna had been sifting through all of the acceptance letters for hours, had she known that sending out this many invitations for her birthday ball that was coming up in two weeks would get this many responses, perhaps she would have invited a few less people. But the thought of all of these people being here in Arendelle, in the castle, dancing the night away and having a wonderful time – well, it was just too much to resist. There was one in particular that she was searching for and she was glad that she had Olaf with her going through these piles of acceptance letters to the invitations, otherwise she would have missed it entirely.

"Oh, I don't know about this one Anna, it has an island name on it. Aren't islands bad?" Olaf asked curiously as he held a pale blue envelope in his hand with a dark blue snowflake wax seal on the back.

"Depends on which island, what does it say?" Anna asked, not paying much attention as she was trying to sort the acceptance letters into stacks.

"Let's see," Olaf said, squinting to try and read the cursive writing better. "Prince…John? No, wait, Jack! Prince Jack Flowers – oh, nope, sorry – Frost, of the Winter Isles. Wow, that's a long name."

"Jack Frost?!" Anna asked excitedly as she grabbed the letter from Olaf and practically ripped it open and read it with a smile plastered on her face. "This is great Olaf, he's coming to the ball!" She squealed.

"Who's coming?" Olaf asked.

"Prince Jack Frost! My cousin told me all about him. Rapunzel's husband went to the Winter Isles before and he found out the Prince was like Elsa so I invited him to the ball and he accepted!" Anna was practically bursting at the seems with excitement now.

"Winter Isles, isn't that the bad one?" Olaf asked.

"No, those are the Southern Isles, these are the winter ones, totally different, and of no relation to the Southern Isles, I double checked." Anna smiled proudly.

"Oh, okay." Olaf smiled now. "Wait, he's like Elsa? How is he like Elsa? Does he have platinum blond hair and wear pretty dresses?"

"Well…I don't know what he looks like really, but I'm sure he doesn't wear dresses Olaf. I meant that he has powers like Elsa, he can control ice and snow." Anna explained.

"Really?" Olaf asked happily. "This is going to be so much fun! I have to go tell Elsa we found her true love." Olaf smiled as he dismounted Anna's bed that he had been sitting on to go through all the letters.

"No! Olaf, you can't." Anna said and grabbed Olaf by his arm to stop him, which only caused his arm to pop off, but Olaf stopped either way and looked back at Anna confused.

"Why can't I tell her?" Olaf asked as Anna put his arm back on his body.

"Because, it's a secret. If you tell Elsa that I invited someone here to kind of be her date for my birthday ball, she'll lock herself up in her room the entire time. If she doesn't know, she'll have no choice but to at least meet him before shutting herself into her room." Anna elaborated with a proud smile on her face as if she had every detail of her plan figured out. "If she meets him though, I'm sure she'll realize they're meant to be. I mean, what are the odds of there being someone else out there like her and them not being each other's true love?"

"Well, I'm no expert at math, but I can try…" Olaf sighed and Anna could see the little snowman getting lost in thought trying to figure out the odds, which caused her to laugh.

"Don't worry about it Olaf, I'm sure it's a pretty big number. Just, please don't tell Elsa about Jack, alright?" Anna asked.

"Right, tell Elsa about Jack." Olaf nodded with a determined look on his face.

"No! Don't tell Elsa about Jack." Anna said.

"Right, don't tell Elsa about Jack." Olaf repeated with the same certainty and determination as before.

"Good." Anna smiled. "Now come on, help me get all these stacked up into piles. I have to let the staff know how many people are coming early and staying and which ones are coming just for the ball."

"Happy to help." Olaf smiled in return and stopped to look at the pile of letters on the floor and sighed. "Oh boy, this is going to take a while."