Valeryk

Valeryk, in this image (see why it's kind of bad later) appears to be an icy blue draft horse stallion with a knotted sea-blue mane and tail (not shown).

Valeryk began his days long ago before Sigga Rolandotter left North of North. She put him in charge of a herd in which he named Valeryk. Once she was banished, the royal herds began to crumble. And so he chose Thunder to be the patron of his herd and they rebuilt it together into what we know it to be today.

Unfortunately, there is only one existing picture of Valeryk, and he's a carousel horse in Spring Carnival (meaning he is all dressed up so we don't know what he really looks like). If you look at the photo of Valeryk, you will see that the illustrator has the horse's proportions off a bit making the whole thing look small.