As Cold and Unforgiving as Winter Itself

On a trip to collect a child's lost tooth, Toothiana unexpectedly finds Jack Frost with the child, and quickly learns about the unpleasant reason for the tooth being lost. When the visit ends up going from bad to worse, she sees a side of Jack that she never expected and will likely never forget.

The Black Ice (Jack Frost/Pitch Black) in this fic is minor and toward the end but nonetheless blatant, so I still tagged for it just in case. But mostly this is focused on Jack and just how far he'll go to protect the innocent.