I am sorry if this a noobish question but what are the snow fairies for that randomly pop up? Is there a certain thing to do with them? For instance, do I have to collect one of each color for an achievement? Or are they just there as minions for pets?

there are several achievements

Fairy Catcher! Get fairies through a random event or catch one floating sometime in December. (highest tier, 500 fairies)

Fairy Collector Have each of the fairies in your inventory, and view your inventory!

Free all the Fairies! Free 1,000 Fairies to continue their good work for Melody!

[edit] Note: doesn't float so it will need to be purchased or borrowed to get the Fairy Collector achievement

Thank you very much, I love getting achievements!