Snowpiercer (слэш)

This is a Dresden Files Snowpiercer AU, with John desperate to get to the front to help his people, while Harry, the security and explosives expert he broke out of prison, just wants to save his daughter.
I found the prompt for this on the Dresden Files Kink Meme, but for the life of me I can't find it again, so hopefully whoever prompted it eventually finds this, and I hope they enjoy it, though it remains stubbornly unfinished.