Firstly, Animagi have to register
Seeing as Harry Potter hangs out with so many unregistered Animagi, we sometimes forget that you’re actually supposed to register if you want to become one. If you don’t, you’re actually supposed to go to Azkaban.
At Hogwarts, students learn about Animagi in their third year Transfiguration class. At the Ugandan school Uagadou, students can master the complex Transfiguration by age 14. But sometimes, like in the case of Wormtail, Padfoot and Prongs, you may not want anyone to know that you have this ability.
The learning process to become an Animagus is… complex
As you might imagine, you can’t just become an Animagus overnight. The learning process involves holding the leaf of a Mandrake in your mouth for an entire month, for example – which is why most students stick to wizard chess when it comes to extra-curricular activities.
Transfiguration and Animagi are different
For example: if Viktor Krum can transfigure his head into a shark’s, like he does in Goblet of Fire, that doesn’t mean he is an Animagus. Transfiguration is a form of spell-casting, whereas becoming an Animagus is forever. Sorry, Krum.
The first recorded Animagus was Ancient Greek wizard Falco Aesalon
And yes, he could turn into a falcon. Lucky.
You cannot choose your Animagus animal
If we could choose our Animagus, you can rest assured we’d all be lions, adorable puppies, or magnificent eagles. But realistically, an Animagus is closely linked to your personality. For example, the brave and rebellious James Potter is famously a stag, whereas the conniving journalist Rita Skeeter is a beetle.
Your Animagus and Patronus animal can be the same
If a wizard never masters Animagus magic, it doesn’t necessarily mean they’ll never find out the animal they could’ve been. Another pretty complex form of magic, the Patronus Charm, has been known to mirror it, meaning the animal you cast to attack Dementors could well be your inner animal too. Minerva McGonagall’s Animagus form, for example, is famously a cat, and so is her Patronus.
Your Animagus may embody a distinguishing feature of your human self
An Animagus may seem the perfect disguise, but once you descend into your animal-self, there may be a distinguishing feature about you that stays. For example, Rita Skeeter’s beetle has little glasses-markings around the eyes, and in the famous case of Wormtail, both he and ‘Scabbers’ were missing a finger.
In North America Animagi were sometimes known as ‘skin walkers’
Native American Animagi seem to have been closely linked to the legend of the skin walkers. The myth told of evil witches or wizards that could transform into animals, and gained their powers through the sacrifice of a family member. This damaging rumour was often perpetuated by fearful No-Maj medicine men.
You do not adopt the life span of the animal you become
Ron was always so bewildered that his pet Scabbers managed to live for so long; 12 years is a very, very old rat. That is, unless you’re actually Peter Pettigrew masquerading as a rat, which in this case was true. This means you could theoretically be an animal for decades, far longer than the animal is supposed to live.