Severus Snape was one of the major characters of the Harry Potter series. His loyalty was questionable throughout the series until his death when Harry visited his memories and saw a reflection of Snape’s whole life: his childhood, his affection for Lily, his rivalry with the Marauders, his time at Hogwarts, his life as a death eater and his life after Lily’s death. Severus Snape’s characters have many complicated layers accounting for his complicated life.
At the beginning of Harry Potter and the Philosopher’s stone, Severus Snape was portrayed as a bully, an outlier, and a recluse. This perception of Snape initially gets better when it is revealed that he tried to fight Quirrell at the end of the Philosopher’s Stone. But after that, his image goes downhill as he is perceived as un-loyal, evil, cold-blooded and a dark wizard whose “real” alliance is unknown to everyone. There were glimpses when Snape shines through and seems less evil than he seems to be, but ultimately he is portrayed as a man who is darker than he is good.
In Harry Potter and the Order Of The Phoenix, while going through a legitimacy lesson with Severus Snape, Harry gets a glimpse into his mind which revealed another aspect of Snape’s life that previously Harry knew nothing about. He only accessed Snape’s mind for a few moments, but in those moments, Harry gained some small semblance of an idea as to why Snape was the way he was.
Harry learned that his father, James Potter, who was one of Snape’s classmates during his Hogwarts years, used to bully him. This made everyone feel sympathy for him but this sympathy is short-lived as the very next year, in Harry Potter and the Half-Blood Prince, Snape is revealed to be a death eater and kills Albus Dumbledore.
Here Severus Snape seemingly betrayed a man who always trusted him. A year after that, in Harry Potter and the Deathly Hallows, Harry, Ron, and Hermione witness Nagini attacking Snape on Voldemort’s orders inside the Shrieking Shack. When Voldemort and Nagini left the premises, Harry approached Snape who was counting his last breaths.
“He did not know why he was doing it, why he was approaching the dying man. He did not know what he felt as he saw Snape’s white face and the fingers trying to staunch the blood wound at his neck. Harry took off the invisibility cloak and looked down upon the man he hates, whose widening black eyes found Harry as he tried to speak. Harry bent over him, and Snape seized the front of his robes and pulled him close.
A terrible rasping, gurgling noise issued from Snape’s throat.
Something more than blood was leaking from Snape. Silvery blue, neither gas nor liquid, it gushed from his mouth and his ears and his eyes, and Harry knew what it was, but did not know what to do-
A flask, conjured from thin air, was thrust into his shaking hands by Hermione. Harry lifted the silvery substance into it with his wand. When the flask was full to the brim, and Snape looked as though there was no blood left in him, his grab on Harry’s robes slackened.
“Look…at…me…” he whispered.
The green eyes found the black, but after a second, something in the depths of the dark pair seemed to vanish, leaving them fixed, blank, and empty. The hand holding Harry thudded to the floor, and Snape moved no more.”
While Harry hated him his whole life, he somehow knew at that moment that he was wrong, that Snape was against Voldemort the whole time. Severus Snape died looking into Harry’s eyes after giving him a portion of his memory. Harry was the offspring of the man who bullied and humiliated Snape his entire childhood, and the woman whom he loved but who didn’t love him back. Harry had the face of his father but his eyes were of his mother, the mother who sacrificed herself for her son. In his final breath, Severus Snape was looking into the eyes which had caused him immense pain but also enabled him to feel love, to feel alive.
Just before dying, Snape instructs harry to collect his memories- memories that could reveal Snape’s full story, helping Harry to understand his tragic life.
“The stone Pensieve lay in the cabinet where it had always been: Harry heaved it onto the desk and poured Snape’s memories into the wide basin with its runic markings around the edge. To escape into someone else’s head would be a blessed relief…nothing that even Snape had left him could be worse than his own thoughts.”
When Harry approached the Pensieve, half of the war had been fought, he had seen Fred, Lupin, Tonks, and many others die, he was exhausted and withered. It was his willingness to escape his own reality that allowed him to fully dive into Snape’s memories and absorb the events of Snape’s life he witnessed.
The memories started when Harry witnessed a young boy who looked like Snape, but unlike the snape Harry knew, this young ten-year-old Severus Snape was happy, he was smiling. Harry also saw his mother Lily who was Snape’s companion. They both lived in the muggle town of Cokeworth with their families. Tragically, this was the happiest time of Snape’s entire life- the period that preceded twenty-seven years of heartache, tragedy, and gloom. Severus Snape and Lily started their journey to Hogwarts together.
However, both of them were sorted into different houses: Severus Snape into Slytherin, and Lily into Gryffindor. This made the pair slowly drift apart as they went down two very different paths. Most of Snape’s housemates were to become followers of Lord Voldemort, and as Snape hung out with this wrong crowd, it made Lily concerned for him. Lily openly expressed these concerns which led to an argument between the two.
In the heat of the moment, Severus Snape calls Lily a “filthy mudblood”, an insult which he immediately and frantically retracted. But it was the last straw for Lily and it ended the friendship between them forever.
Next, harry sees an older snape, begging and pleading with Albus Dumbledore on a hilltop. At that point in time, Severus Snape was a full-fledged death eater and the reason for him pleading with the leader of the opposite “good” side was none other than Lily. Harry begins to understand that Snape had seen Sybill Trelawney, a seer, predicting the fabled “Prophecy” and relayed that information to Voldemort.
When Voldemort concluded that the couple in the prophecy refers to James and Lily and that Voldemort was going to kill Harry, Snape was filled with guilt. Knowing that this would directly put Lily’s life in jeopardy, he had no other choice than to go to Dumbledore- the only wizard that Voldemort feared and the only person powerful enough to directly oppose Voldemort and protect Lily.
The next memory that Harry witnesses is after the tragedy at Godric’s Hollow had taken place after James and Lily had been murdered. Harry sees Snape and Dumbledore in Dumbledore’s office and witnesses Severus Snape agreeing to devote his whole life to Harry, to Harry’s safety, in Lily’s honor.
After reviewing Snape’s memories, Harry begins to see his old potions professor in a new and completely different light. Snape’s murky, bitter death image in Harry’s mind, that he hated, disappeared. In Harry’s heart, there was a place for redemption in Snape. This is reflected in the Epilogue when it is revealed that Harry named one of his own children after a man he has hated for so many years.
Severus Snape wasn’t a dark and troubled an of his own volition, he was a man perpetually haunted by his past. He was neglected by his parents, the one girl that he loved all his life didn’t love him back, saw that same girl marrying a man he loathed, and was later endured a stressful life as a double agent in an ongoing wizarding war.
Severus Snape did bully some of his students, discriminated against Slytherins and the rest of the students, especially Neville Longbottom. He wasn’t perfect and had a darker side to him. That is what makes his character one of the most interesting ones in the whole franchise.