Baby Prisoner of the Winter Castle

On the evening the kingdom fell and the entire royal family faced execution, Clarisse, who assumed she would meet the same fate, heard something surprising.

"We cannot execute anyone who has not reached the age of eighteen. Instead, I will kill you the day you turn eighteen."

Thus, Clarisse is granted ten more years to live.
She then journeys North as a "prisoner."
And she requests from the Grand Duke just one thing…

"Um, is it okay if I take this friend with me? It’s my only friend."

What Clarisse presents is a rock?

It’s a fresh start in the North!
But this existence as a "prisoner" keeps becoming more enjoyable…?