Familiars: what are they?
This is something that comes up every once in a while and lately has been coming up a lot, so we should discuss familiars. It is largely thanks to modern commercialization of misconceptions from the European witch trails that we get our current misunderstandings of familiars. So let's breakdown the history and perceptions of familiars to get a better grasp of them.
Familiars are a kind of tutelary spirit, a non-corporeal intelligence that a witch/magician summons and binds to themselves. In a way, they are like a servant to the witch, but under some conditions. For instance, the magician needs to appease their familiar to keep its company. If a familiar feels that the magician has violated the terms of their pact, they will leave and may even harm the magician. Likewise, if the magician were no longer happy with the services their familiar provided, or they felt their familiar was leading them into danger, they would banish them or call on another spirit to send it away forever. Ultimately, assuming a good bond has been made, the familiar will stay with the magician for the remainder of the magician's life, as familiars do not die. They're spirits, so they don't die. They will assist in magical practices, teach, heal, fetch money, fetch mightier spirits to help, et al. In return the magician will give shelter, food, water, and whatever else the witch-familiar compact may have an agreement on.
The oldest and closest thing we have to the modern idea of a familiar are the household gods of the ancient world. Even as cities developed, individual households had their own gods. It isn't until much later that we see cities and states develop their own "household gods" or gods of the city.
Prior to the Romans there does not seem to be much of a distinction between household gods and the larger religion gods. But the Romans had three different names for these sorts of spirits that give us some clear distinctions of the perceptions these people had of their gods: genius loci, dii familiares, and lares. The genii loci were "spirits of place," and were spirits that governed and protected a specific area, such as a neighborhood, a crossroad, a forest, etc. Genii loci that governed a household were called lares. These were the household gods that residents set up shrines to just inside the doorway, a common practice to this day. Then there were the dii familiares, which were something like the lares, but watched over the whole family, as the family did not always stay in the home, but expanded, moved, went to the market, etc. If these household gods were not kept happy, they would leave the house and family, leaving them unprotected, and may even come back to harm them.
We see evidence of this in the Bible, particularly in Genesis where Rachel steals her father's household idols. Eventually there would be state genii loci, lares, and dii familiares, such as Roma personified as a goddess in her own right. Hermes was also a genius loci, usually at crossroads. Enodia (Hecate) was another crossroads genius loci. However these two gods become more state religion deities with their servant spirits watching over crossroads. Jehovah is very much like this with the ancient Israelites, even having a pact, i.e. the Covenant, of which the Ark of the Covenant was a fetish object to house God.
However, truly the oldest idea of a familiar is the personal daimon or demon, a specific daimon that is assigned to each person at birth. The oldest complete example of conjuring a personal daimon is described in the first portion of the Greek Magical Papyri, a collection of magical spells and rites dating between 1st century BC to 5th century AD. This rite details how to conjure a daimon that will be bound to the magician, and will teach and guide them, dine and sleep with them, and be with them until the end of the magician's days. Socrates himself may have had something like this when he refers to his daimonion, a "divine something" that advised and guided him, but never controlling him.
This personal daimon becomes a central feature of western magic. In Byzantine magic, such as in the Hygromanteia, the daimon becomes something akin to the dii familiares, though distinctly personal to the magician and the same familiar can be passed from master magician to apprentice (such as Dr. Faustus to his pupil). All grimoires been the 13th and 18th centuries have a rite to conjure a familiar or to conjure a spirit to bring a familiar. A great example of this is in the Ars Goetia where several demons are listed as being good for bringing familiars. Similar examples are found in spirit registers such as in the Grimorium Verum. Even folk magic includes ways of gaining a familiar, and the rites are usually a lot more simple than the formal ceremonial magic of the Renaissance grimoires. These are found in various Secreti or books of secrets (see for instance Treatise of Magical Secrets and Mixed Cabala, trans. by Rankine and Skinner)
Our current conceptions of a familiar come from the witch trails of the 16th and 17th centuries. Prior to this time period magic was not exactly forbidden. Magic was usually something that was tacked onto other charges, usually treason. Since magicians held their reputations via rumors and recommendations, and rumors are what Oliver Cromwell sought to destroy, thus witchcraft enters the courtroom thanks to such rumors of magicians. As witchcraft becomes chargeable on its own in the 16th century, we see players like Matthew Hopkins enter the stage. These "witch hunters" were nothing more than opportunistic assholes who used Cromwell's methods of hunting via rumors. Anything could be used as evidence of a witch, and townsfolk often used these opportunities to get rid of someone they didn't like by accusing them of witchcraft. Most of the people, usually women, though there were plenty of men tried as well, who were accused of witchcraft were not actually witches. They could just be lonely old widows that have a dog or a cat to keep them company.
Familiars, or rather pets, were a common way of determining if someone was a witch, since that was part of being a witch. However, people back then had pets like anyone today. So these women who were seen as unusual and therefore a witch, had their pets used as evidence against them. And really, they were like many of us: they had a close relationship with their pets, talked to them, really cared for them, took them everywhere with them. This all sounds strangely like a familiar, and to opportunists like Hopkins, it was the perfect rumor to locate a "witch." But really it was just an excuse to kill a quirky old woman no one liked who lived alone and loved to talk to her birds, and someone else probably really wanted her land.
Much of this pet as a familiar has become sensationalized today. In a way, yes, you can conjure a familiar to inhabit the body of your pet. In the Renaissance, possessing an animal with a spirit was no big deal. Today that would probably be seen as unethical to your pet. But there really is no need for this, as a spirit will physically appear to a magician at their command, and can even take on familiar forms such as a dog if the magician requests it. It is not uncommon to see in Renaissance grimoires a portion of the conjuration includes the magician stating, "appear to me in a pleasing form."
Further, it's borderline animal abuse to truly treat your pet like a familiar. A lot of energy is exhausted by familiars to be your servant, but they're spirits and can usually handle it, and if they can't, they go get you a bigger stronger spirit to handle it. Pets cannot do that, and they shouldn't have to. To truly use your pet as a familiar will most likely harm them in the long run. Pets should be treated like family, not your magical teacher and conduit.
In practice, the familiar can be almost any kind of spirit. In the Abramelin rite the familiar is called the Holy Guardian Angel, a divine heavenly entity assigned to each person at birth. In the Faustian tradition, the demon Mephistopheles is Dr. Faustus's familiar. In the Christian tradition, the Holy Spirit acts as a sort of familiar to Jesus, assisting Jesus with his miracles, and according to Paul raised Jesus from death. But familiars can also be souls of the dead, such as ancestors. In fact, the lares and dii familiares may have been ancestors of that family/household that always stuck around to watch over everyone, and later became deified.
So while our pets are very important to us and can even be a bit magical, they are not the same as a familiar. And in many ways it's wrong to say they are. It takes something that was viciously used to torture and kill lonely old women and sensationalizes it into an aesthetic, rather than a way of life, a devotion, and a compact you keep and renew each and every day with the same entity. And to make your pet an actual familiar is abusive. Having a tutelary spirit (or several) is central to western magical practices, but it is not the same as having a pet. If you want to get a pet, get a pet. If you want a familiar, there are hundreds of ways to conjure one up and make a lifelong pact with it.
The reason this is important to understand and differentiate is so you become a better pet owner and a better witch.
Image: Matthew Hopkins, "Witch Finder General" (a title he made up) investigating witches and their familiars.