Rise Of The Big Four

When Merida misses her friends, she goes into the forest for a picnic with the Triplets and Angus to clear her mind. What frosty friend will she meet there and what does he need Merida for? What does the Man in the moon want with the big four? Will contain Jack/Hiccup bromance (not gay) and very slight Merida/Rapunzel that increases to something more later on.