I believe Farron Keep to be Oolacile/Darkroot Garden which is where you use the Crest of Artorias, they hint at it being Oolacile through the yellowfinger heysel invasion where they wear the Xanthous set which scholars of oolacile used not just that but this is where you can find golden sorceries of oolacile, and the great wolf of Farron, Farron meaning iron grey, its a giant wolf, so? Great wolf of Iron Grey, Great Greywolf Sif, also the Ghru look alot like the abyss corrupted guys from the dlc.