Bigby's Vengeance is one of the unlockable Book of Fables entries that the player can get in Episode 1 of The Wolf Among Us. It is unlocked by choosing to rip Grendel's arm off after fighting him in the Trip Trap.
Entry
Long ago in the Homelands, the North Wind fell in love with a blazing white she-wolf. Taking canine form, he courted her and stayed by her side for two seasons. However, the wind by nature must change direction and North's temperament carried him back to his wintery castle. The she-wolf was heart-broken, and soon after her lover fled, she gave birth to a litter of cubs, including the one that would become the Big Bad Wolf of legend. Watching his mother die of sadness and unrequited love, young Bigby swore vengeance against the capricius North Wind. Seven times the beast journeyed to the great castle, but was no match for the elemental might of his father. Having failed to taste vengeance, he swore to think no more of his dead mother or loathsome father. Buried hatred, however, is seldom forgotten.