At the end of the first Frozen movie, we see Anna and Kristoff together and in love. The iceman is now part of the family and they all live happily together. At the 'Frozen Country Day' earlier in October, Disney revealed a clip where Elsa, Anna and Kristoff along with snowman Olaf and reindeer Sven are having a family night, playing charades. That is when Elsa first hears a haunting call and has to interrupt the game night early to retire as she tries to block out this beckoning voice.
Kristoff takes the opportunity to pop the question to Anna, well almost pop the question. A distracted Anna is worried about her sister's strange behaviour and is completely oblivious to Kristoff's plans. Though Anna loves Kristoff deeply, Kristoff's proposal plans always go awry. Later, when Elsa decides to venture into the unknown, Kristoff does not hesitate to join the sisters on their journey to distant lands that even the well-travelled iceman has never been to before. Kristoff remains best pals with Sven and leans on him, especially when his attempts to propose to Anna get interrupted.
Kristoff still voices Sven like he used to (for the uninitiated, Sven can't speak), and when the sisters set off on an adventure, the trusted reindeer comes along.
Kristoff, the charming iceman, meets Anna and Elsa in the first movie but their association, even if tenuous, goes back a long way. We saw a young Kristoff, chancing upon little Elsa who is brought by her parents to the trolls for treatment for her magic powers. That memory is etched in boy Kristoff's memory and shows that he was in on the secret much before everyone else.
As far as we can see in the trailer, it is Kristoff's mission to be the anchor while the love of his life, Anna gets swept up in a new adventure.