A particularly wild theory about the new characters' identity we can't shake is, what if the kids are people from Arendelle's past? Specifically, their late king and queen? Before you click away, just hear us out! What if we discover that Elsa's powers are genetic (as mentioned previously) and this scene is a flashback to her parents as children when they were able to play about freely. The two look enough like their parents, albeit younger, and it would explain their clothing. The young man could be their father, a royal, and their mother could have been someone of more common origin. We're just saying, there are so many possibilities, we can't rule it out!