Pluviae

Glacies and Pluviae, code-named by their parents as the Pale Twins, do everything together. They finish each others' sentences, compulsively borrow from each other, and always share food, to the point that if they are separated, neither will eat. They might sleep if they're on their own, but usually they sleep curled around each other.
They are quiet, dry-witted children who perform little mutinies against their parents, Perryn, and Urbei. They can exchange teasing jokes about others to themselves with just a glance. They won't play pranks outright, but they will stand by and quietly judge their friends who put together a practical joke, muttering to each other in sync about how it could be done better.
The Pale Twins are so similar that they are only told apart by their hobbies. Pluviae likes climbing. He likes trees, mountains, piles of rocks, piles of snow. Dog-piles of dragon hatchlings. He always wants to climb to the top, because he likes the view from up high. Glacies will come with him, boost him up if he needs it, but usually his twin will wait at the bottom for him to come down again, since he isn't overly fond of heights. But, he puts up with Pluviae's hobby, and Pluviae puts up with his.