So I was watching Game of Thrones and had an urge to
TRY and find any good fanfiction.
Shocker: I found one crossover that's steadily updating and I'm LOVING how its written.
The Prince Who Was Promised
SUMMERY: He remembered being Harry Potter. Dreamed of it. He dreams of the Great Other too, a creature of ice and death, with eyes red as blood and an army of cold, dead things. He is only the 2nd son of the King, a 'spare', but that changes when things rather left in the dark come to light, and Westeros is torn asunder by treachery and ambition. Winter is coming... but magic is might.
YES, a SoIaF/HP crossover and it doesn't suck! Try it, be surprised, love it.
EDIT: I was shocked to discover this had also been linked in the HP thread here so consider this a second recommendation.