Fables is one of the few stories discussed in which knowledge is withheld for the greater good, rather than individual gain. Bigby Wolf keep many of his discoveries secret while investigating Rose Red’s murder case, until his grand finale when he gathers all the fables and reveals that Rose Red faked her own murder.
This panel of the comic comes from Snow White’s brief confrontation with Bigby during his reveal, when she lashes out as him for not letting her know that her sister was still alive. He soon informs her that he was unsure whether Rose was still alive until just several hours prior, and he didn’t want to inform Snow that her sister was still alive and turn out to be wrong. Everything he has kept secret from Snow and the larger fable community was so that he could finish his investigation without conflict or interruption. His secretive tendencies somewhat mirror those of Dr. Moreau is the beginning of the Island of Dr. Moreau, however Bigby’s motives are eventually revealed to be beneficial rather than somewhat sinister.
Related: The Island of Dr. Moreau