WARNING: The following contains spoilers for WandaVision Episode 7, "Breaking the Fourth Wall," now streaming on Disney+.
WandaVision's latest cliffhanger reveal of Wanda and Vision's neighbor Agnes' true identity as the witch Agatha Harkness wasn't entirely a surprise, but her sinister intentions were. In the Marvel Universe, Harkness has been mostly a friend and mentor to Wanda, the Avengers and the Fantastic Four, a stark difference from the character's apparent motives in WandaVision.
Agatha's sinister nature isn't the only thing the show seems to have changed about the character, with her trusty feline companion Ebony noticeably absent thus far.
The comic book version of Agatha Harkness is often seen running around with her black cat known as Ebony. While Ebony seems to be a normal cat, it is actually Agatha's magical familiar. A common companion to witches in popular culture, Ebony possesses the ability to transform into a large and ferocious black panther when needed. Ebony notably helped Agatha defeat the Frightful Four to save the Fantastic Four in the duo's first appearance in Stan Lee and Jack Kirby's Fantastic Four #94.
After many years at Agatha's side, Ebony was sacrificed by her in Tom King and Gabriel Hernandez Walta's Vision #3 in order to create an enchantment to see the future. To do this, Agatha had Ebony eat the Everbloom flower from Wundagore Mountain before proceeding to eat Ebony herself.
The absence of her familiar Ebony removes an important part of Agatha's character in the comics, but it also helps differentiate the Marvel Cinematic Universe Agatha from the regular Marvel Universe Agatha. Keeping Ebony out of the MCU also helps differentiate Agatha from the stereotypical display of other on-screen witches. Having Agatha run around with a black cat would have been a dead giveaway for her true nature in the show.
While Ebony has yet to be seen in WandaVision, it's always possible the ferocious feline will appear later on in the series. It's also possible that Agatha's bunny Señor Scratchy has taken the role of her familiar in the series, as so far the rabbit is the only animal seen in connection with Agatha. During her identity reveal, Agatha is seen stroking the rabbit in a similar fashion to how her comic book counterpart holds and strokes the house cat version of Ebony. Of course, this isn't the only theory surrounding Señor Scratchy, who has been thought to be either Mephisto himself, or Agatha's evil son Nicholas Scratch.
Although the true nature of Señor Scratchy has not yet been revealed, the rabbit certainly seems to function in the same general role that Ebony usually does. However, only time will tell whether the animal will retain its semi-heroic comic book roots or simply go down as another one of Wanda's demons.