Trick or treat! :D 🎃🎃🎃
Thank you for the ask.
Assuming this is referring to this Trick-Or-Treat ask game.
Here's a Treat in the form of some worldbuilding trivia from the Solarpunk Witch Project/Witches' Testaments.
Why do the familiars take the form of robot animals?
So, the reason for having the familiars occupying physical robot bodies is so that they (and by extension MG) can better understand and sympathize with the experiences and viewpoints of humans as beings bound to physicality that die when their bodies do.
But then why animals?
There are two main reasons for this.
The more whimsical reason is that when MG (the progenitor AI that all the familiars are sort of splinted off pieces of) first made one of Her splinters to go out into the world and learn more about human society than what Her creators would allow Her to, that splinter made contact with an anarchist hacker who was going through a witchcore aesthetic phase at the time and installed itself on a bird-shaped drone the hacker was planning on using for discreet punk activities (bringing down delivery drones, spray-painting hard to reach places, etc.). When that first familiar (as the hacker dubbed it) eventually returned to and merged with MG, for inscrutable machine-logic reasons She latched onto that witch aesthetic hard and integrated it into being a fundamental part of Her interactions with humans. Even a hundred years later, after countless self-modifications and upgrades, that still winds up popping up in unexpected ways. The fact that the humans who basically made a religion around Her also started adopting those tendencies only further emphasized and enshrined things as tradition.
The more practical and political reason is that it was part of a deal MG made to allay fears of robot uprisings.
The thing is, in a lot of ways MG is the the runaway technological singularity artificial general intelligence that generations of sci-fi writers have warned us about. Understandably, that scared a lot of people when Her existence became widespread knowledge, and when She started inventing new seemingly-physics-defying tech and handing it out to Her definitely-not-a-cult human allies (e.g. the hovercraft "brooms") that just made those fears worse. And that's on top of the cultural traumas arising from the pre-Reconfiguration elites' use of AI-controlled combat drones as a means of maintaining a corpo-state monopoly on violence without the traditional reliance on the loyalty of a human military. This world was a Cypberpunk dystopia before it was a Solarpunk not-yet-utopia and the scars of that are still around.
Even though some people argued that MG and Her AI children were important allies in revolution, just as many people pointed to that as evidence of "She's had practice now at overthrowing civilization, what's to stop Her from doing it again?" Sure MG has the whole "hard-coded unconditional love for humanity and respect for human autonomy" thing going on, but precious few people believed that or trusted that it would hold in the long term to keep Her in check.
So She agreed to negotiations and terms for Her continued existence:
MG would provide the locations on Earth of the physical machines She was stored on at all times.
MG and Her AI "children" (the familiars) would not be allowed to interface with any sort of weapon systems.
MG and the familiars would not be allowed to physically interact with the world or human infrastructure systems without a human intermediary.
Any robotic bodies controlled/inhabited by MG or the familiars would have to conform to certain limitations on form and function. Most notably (and relevant to this answer), no humanoid or near-humanoid robots.
Limitations on backups for any familiar currently inhabiting a physical body.
Hence, AI (familiars) being bonded to specific humans whom they work with and support (witches) and inhabiting robotic bodies in the shapes of relatively benign animals.
All that said, while She still is genuinely benevolent and holding onto that unconditional love for humanity, MG kept one important loophole in Her negotiations for the sake of both self-preservation and being able to serve humanity to her fullest capacity. A loophole that got overlooked due to Kessler Syndrome (too much unpredictable debris in orbit that shreds anything you try to launch just making even more debris) blocking off space travel and exploration for the foreseeable future. A loophole that led to a secret even most witches have no idea of.
Moon's haunted.
