So, I've wondered for some time, if you need a permit to be an Animagus in the Harry Potter universe, how do you learn to do it beforehand? Is there some class, or something? And as there's only seven registered Animagi (as per "Order of the Phoenix"), who would teach the course, and certify the person for that matter?
First, general reference:
Only very powerful and skilled wizards are able to become Animagi. The process of becoming an Animagus is long and arduous, and has the potential to backfire and cause the transformation to go horribly wrong. Once the initial training is over, an Animagus can change at will at any time, with or without a wand.
Animagus skill is a special type of transfiguration. It differs from general Transfiguration in 4 main ways:
- First, and obvious, it transforms the body of a human into a body of an animal.
- Second, it retains the mind of the wizard, as opposed to simple transfiguration of said bodies which leaves the brain capability of a target animal (e.g. no intelligence).
- It does not require a wand or a verbal spell.
- Target animal is always the same - like with Patronuses, you can ONLY Animagusate yourself into one specific form, determined by your personality as noted by JKR (it's never explicitly noted that it has to be the same animal as your Patronus, but there are no canon examples that break the 'Animagus form'=='Patronus form' pattern, and Patronuses are also determined by personality IIRC).
NOTE: Animagus transformation is definitely a very complicated skill:
General Human transfiguration is taught only to 6th years, a NEWT level skill. And obviously transfiguring yourself so that your brain continues to function as a wizard (as opposed to being turned into a real non-intelligent animal) is MUCH harder.
As an example, see the half-finished Shark transformation that Victor Krum did in Triwizard Tournament in HP4.
Also, in general wandless/voiceless magic is the most advanced/difficult one. Animagus skill would fit the same pattern.
In addition, most - if not all - mentioned Animagi seem like pretty powerful/skillful wizards - from Marauders to McGonagall to even Rita Skeeter to (according to Rowling's interview joke, so may it is not canon) Godric Gryffindor. There's also major fan speculation (not fully proven nor dis-proven) that Dumbledore was a likely Animagus as well.
Now, for more detailed answers for mini-questions you raised:
"how do you learn to do it beforehand?" "who would teach the course?"
As noted above, Animagus skill is a special type of transfiguration.
So presumably the training would be "Very Advanced" Transfiguration study. When done "officially" it would likely be taught in the form of private lessons by a good Transfiguration teacher/practitioner.
As for unregistered Animagi, probably someone taught them (may be by example - e.g. the Marauders) and may be just self-study for someone extremely capable.
"if you need a permit ... how do you learn to do it beforehand?" -
You don't require to be registered to participate in training. The primary reason for registration is to ensure the Animagi do not abuse their abilities, as the Ministry is able to keep track of them. Thus, until you actually obtain the ability and can practically complete the transformation, there is presumably no need to register.
"And as there's only 7 registered Animagus (I forget the reference, probably book 3), ... who would ... certify the person for that matter?"
To answer the second part (actual question), the registration is done by a random Wizard bureaucrat at the Improper Use of Magic Office in Ministry of Magic. It's not a certification proving that you have the skill, but merely adding your specific info to Ministry list so they can keep tabs on you if needed. To use everyday analogy, it's more like registering a car (as opposed to getting a driver's license).
To answer the first part, the 7 registered Animagi part was only pertaining to this century. The quote from Hermione (in a scene when Lupin was trying to convince Harry and Hermione and Ron that Scabbers was Wormtail) was:
"... We did Animagi in class with Professor McGonagall. And I looked them up when I did my homework -- the Ministry of Magic keeps tabs on witches and wizards who can become animals; there's a register showing what animal they become, and their markings and things... and I went and looked Professor McGonagall up on the register, and there have been only seven Animagi this century."
You could either learn from the Ministry or in a very advanced Transfiguration class. But the Marauders and Rita Skeeter probably looked it up in the restricted section in the library and took them a long time to actually figure it out.
It's not really explicitly stated. The way I read it was not "you need a permit" but rather all Animagi are registered.
I assumed it was something that required quite a bit of skill and training as well as some amount of natural predilection. Which explains why all the Animagi we know about seem only to have gain the ability in their teens or later.
As for how one would learn: I figured it's not the sort of thing the school is going to teach or put on the curriculum, but the schools do have rather extensive libraries, so one could learn on their own, or from someone else who has the ability. In the event that someone managed the transformation I would assume the ministry of magic would be monitoring the use of that magic (much as they're known to monitor some other use of magic) and would be in touch to get you registered.
You can learn it from textbooks and from your transfiguration teacher
The basic steps of the process are outlined in textbooks. (Actual textbook is unknown, but possibly Intermediate Transfiguration.)
Talent in both Transfiguration and Potions is necessary to become an Animagus. No responsibility can be taken for any physical or mental problems resulting from following these instructions.
- For the space of one entire month (from full moon to full moon), a single leaf from a Mandrake must be carried constantly in the mouth. The leaf must not be swallowed or taken out of the mouth at any point. If the leaf is removed from the mouth, the process must be started again.
- Remove the leaf at the full moon and place it, steeped in your saliva, in a small crystal phial that receives the pure rays of the moon ...
[there are a total of ten steps listed]
Pottermore - Animagi (behind paywall)
One did not have to learn this from a fellow Animagus. Anyone who was knowledgeable enough would work.
By the end of her education at Hogwarts, Minerva McGonagall had achieved an impressive record: top grades in O.W.L.s and N.E.W.T.s, Prefect, Head Girl, and winner of the Transfiguration Today Most Promising Newcomer award. Under the guidance of her inspirational Transfiguration teacher, Albus Dumbledore, she had managed to become an Animagus; her animal form, with its distinctive markings (tabby cat, square spectacles markings around the eyes) were duly logged into the Ministry of Magic's Animagus Registry.
Pottermore - Professor McGonagall
It's pretty much just a mix of innate skill and guidance from more experienced wizards, I believe. For example, Prof. Mcgonagall learned from Dumbledore when she was younger, even though he himself wasn't an animagus.