It's a long, complicated process.
As a pack animal, or as a “lone wolf,” the wolf is a perfect fit for Harry's Animagus form.
Because to process was so difficult and dangerous, and because many witches and wizards simply felt that their time might be better spent in other ways, not many people chose to try becoming an Animagus. Besides that, the skill was of limited practical use anyway, unless one had a great need of disguise or concealment.
However, if nothing happens, they will know something has gone wrong. They must start over, which is likely why the Maraudersof Harry Potter were unsuccessful at becoming Animagi until their fifth year at Hogwarts.
It took skill, practice, and patience for wizards and witches to become Animagi. The process of becoming an Animagus was long and arduous, and had the potential to backfire and cause the transformation to go horribly wrong.
Animagus. Lily's animagus form is a Doe, coupling with her husband, James Potter who is a Stag. Severus Snape's animagus is also a Doe.
At the time, he thought Sirius murdered his best friends, and was after Harry. Lupin had to think that it was a possibility that Sirius was transforming in order to evade capture.
Usually people turn into Animagi who match their Patronus, so it is safe to assume Snape would be a doe. But based on his morals qualities, I'd say maybe some kind of prey bird; a crow would be the perfect match.
Being an animagus wasn't Dark magic, nor particularly useful for ruling over everyone, nor for genocide, nor for achieving immortality, nor for infamy, so Voldy never bothered to become an animagus.
In the Harry Potter books, only a few Animagi (registered and unregistered alike) are even mentioned. They are James Potter, Sirius, Wormtail, Skeeter, McGonagall, Talbott Winger, and an unnamed witch who can turn into a cat. The fact that there are so few Animagi just causes us fans to want to know more about them.
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. And yes, he could turn into a falcon. Lucky.
In the films, Hermione's Patronus is depicted as a European River Otter, and her Animagus form would most likely be the same animal, as confirmed by author J.K. Rowling.
Following both ordeals, Ginny grew into a confident young woman. Her and her friends followed in the footsteps of a previous generation, completely unbeknownst to them, and became Animagi at the age of fourteen, to support their best friend, Maisie Cattermole. Ginny took the form of a grey mare.
Sirius Black and James Potter attended Hogwarts together, and Sirius is Harry's godfather. Sirius is an Animagus, which means he can transform himself into a black, shaggy dog named Padfoot at will.
Draco is not an animagus in the story. However, if he were to become one, I believe he would be a Siamese cat. His belief in his superiority and his snobbish manner line up with Siamese traits, but he, like the cats, loves his family deeply.
He is seen in his animagus form by Lucius Malfoy while on Platform 9 3/4. Lucius, as a Death Eater, knows about Sirius' animagus form because Peter Pettigrew told the Death Eaters when he returned to their side after book 3.
Extremely intelligent, exceedingly talented and a "wicked" Animagus, it's no wonder Minerva McGonagall is Head of Gryffindor house.
Was Voldemort an Animagus? No, Voldemort was not an Animagus. He didn't see any reason to become an Animagus despite being a gifted wizard and knowing a lot of magic. This may simply be because his sole purpose was to obtain immortality and become the strongest wizard who could control the world around him.
He rejected his family's pure-blood elitism and reverence for the Dark Arts. At Hogwarts, rather than be sorted into Slytherin like the rest of his family, Sirius was placed in Gryffindor.
Sirius was an animagus and was able to transform into a big black dog, (a Grim) which is an omen of death, at will. He, along with James Potter and Peter Pettigrew became Animagus to help Remus Lupin with his transformations.
James Potter
Werewolves might be dangerous to humans, but they don't attack other animals; so Lupin's friends found a way to stay together as a kind of pack. James's Animagus form was that of a stag, which earned him his nickname, Prongs.
Falco Aesalon — Falcon; the first recorded Animagus; the registration system was not in existence in his time. Morgan le Fay — Bird; the registration system was not in existence in her time. Minerva McGonagall — Tabby cat; registered. James Potter — Large stag; unregistered.
And there is no question that Snape was a talented wizard, and that he could have become one if he had wanted to. But the fact is, there is not one single shred of evidence in Canon that Snape ever became an animagus.