Patronus Charm is a complex one, and throughout the books, there is mention of only 22 wizards that we know could perform the Charm. Severus Snape is one of them.
As we all know, the Patronus takes a different shape for different people and usually mirrors one’s character and feelings.
What was Snape’s Original Patronus?
During the course of the Harry Potter saga, we never earned what young Severus Snape’s Patronus was or when he learned it.
We know that Snape’s Patronus was a doe in his adult life. We learned about it from the chapter The Prince’s Tale of the book Harry Potter and Deathly Hallows.
We can’t be sure if the doe was his original Patronus. We don’t know when students at Hogwarts learn this kind of Charm.
We can only assume it would be during their sixth or seventh year since Professor Toffty, Harry’s O.W.L examiner, was surprised to hear that Harry, a 15-year-old student, could produce a corporeal Patronus.
We guess that Snape’s Patronus could have a different form in school. He was as much in love with Lily back then as he was as an adult, but we think that before she died, he never realized how much. He could have been occupied with his Death Eater tasks to pay as much attention.
Why is Snapes’s Patronus a Doe?
Snape’s Patronus was a doe because he loved Lily, whose Patronus was also a doe.
Snape didn’t have a happy childhood. His father didn’t like many things and always took his anger on young Severus and his mother.
Snape took refuge outside, wandering the streets. It was there he met Lily Evans, and because they both could perform magic, they ended up being friends. Lily ended up being Snape’s only friend for a long time.
It is easy to see why Snape fell in love with Lily. She was the only person defending him from bullies, the only person he confined in. And she was a beautiful girl.
Snape regretted the fallout between them dearly, and after the events of Halloween 1981, he blamed himself for Lily’s death. His doe Patronus was the result of his feelings for Lily and his regret and devastation after her death.
Are Snape and Lily’s Patronuses the Same?
We know, from J.K. Rowling, that Lily’s Patronus was a doe. And after reading chapter thirty-three of the last Harry Potter book, we know that Snape’s Patronus is a doe as well.
Even though Harry never knew about his father’s Patronus and never mentioned his mother’s one, he seemed familiar with a doe Patronus. It is possible that his mother performed a Patronus Charm when Harry was little.
Harry stared at the creature, filled with wonder, not at her [doe] strangeness, but at her inexplicable familiarity.
Seeing Snape’s doe, Harry felt safe, and acting on instinct, he followed the doe through the Forest of Dean. We think that because the doe Patronus conjured by Snape was a replica of Harry’s mother’s Patronus, Harry felt a connection with it.
Did Snape’s Patronus Change?
The form of a corporeal Patronus usually depends on one’s secret self that lies within. It can also change when one grieves, falls in love or changes his character in other ways. It is highly possible that Snapes Patronus changed after Lily’s death.
We know that Snape was deeply in love with Lily since his childhood, and he begged for her protection from both Voldemort and Dumbledore. Losing her would have been a blow to Snape. There is plenty of evidence that Snape took it badly.
“Her son lives. He has her eyes, precisely her eyes. You remember the shape and color of Lily Evan’s eyes, I am sure?”
“DON’T!” bellowed Snape. “Gone… dead…”
And next, Snape was kneeling in Sirius’s old bedroom. Tears were dripping from the end of his hooked nose as he read the old letter from Lily. (…)
Snape took the page bearing Lily’s signature, and her love, and tucked it inside his robes.
Loving someone and losing them will heavily influence one’s Patronus, and though we don’t know Snape’s original Patronus, we can guess that if it weren’t a doe from the start, it would change after the loss he experienced.
Dramatic events in Godric’s Hallow in 1981 had an impact not only on Harry but also on Snape. The love of his life died there, and Snape believed it was his fault.
We are not sure if Snape’s Patronus changed after Lily’s death or if it was always a doe, but we believe that his strong feelings for the only true friend he ever had an impact on the form of Snape’s Patronus either way.