Re: A Song of Ice and Fire books
I think the fanfiction mention was meant to indicate novels within the world of ASOIAF written by someone other than Martin. Shared world novels, such as the various dungeons and dragons novels or tie-ins like the Star Wars EU, are frequently referred to as "fanfiction."
"I defeated your uncle Victarion and his Iron Fleet off Fair Isle, the first time your father crowned himself. I held Storm's End against the power of the Reach for a year, and took Dragonstone from the Targaryens. I smashed Mance Rayder at the Wall, though he had twenty times my numbers. Tell me, turncloak, what battles has the Bastard of Bolton ever won that I should fear him?" - Stannis Baratheon