Any fics where Sam leaves the motel, either having a fight with Dean or just gone out for dinner for them or something and he gets stuck in the snow and has to walk back, he calls Dean's and his brother has to guide him back to the motel safely.

Bonus points if Sam is close to hypothermia and starts to lose it and eventually when he's close enough to the motel Dean is there outside to catch him just before he collapses.

I don't mind if Dean is stuck either, or the boys are stuck together and one is freezing their butt off and starts to get sick.