Snape having the same Patronus, the doe, as Lily symbolized his everlasting love and unwavering devotion towards her. He hadn't stopped loving her after their last altercation, marriage to James Potter, or death. She was his "always," his guiding light, and he protected Harry for her.
As "Harry Potter" fans will recall, the word "always" comes from a scene in which Snape reveals to Professor Albus Dumbledore that he has always loved and will always love Harry's mother, Lily. Ultimately, this revelation allowed Rickman to understand that Snape was not entirely evil.
For the Potter uninitiated, “always” is how Snape explains to Dumbledore in the final book why his Patronus takes the same shape as the one belonging to his long-lost love: Harry Potter's mother, Lily.
Lily has been dead for 15 years, so Dumbledore says “after all this time” (meaning Severus still loves Lily after 15 years?) With a look of anguish on his face, Severus replies “Always”, meaning he has loved her always. He loved her as a child, a school boy, and still now, even after her death.
Now, as firmly established, Snape was not the greatest fan of Harry, but that didn't mean that he ever stopped loving Lily. Dumbledore was surprised that Snape seemed to care for the boy. With a swish of his wand, Snape conjured up a Patronus – Lily's Patronus, a doe. 'Always,' he said.
“You disgust me,” said Dumbledore, and Harry had never heard so much contempt in his voice. Snape seemed to shrink a little, “You do not care, then, about the deaths of her husband and child? They can die, as long as you have what you want?” Snape said nothing, but merely looked up at Dumbledore.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
A Professor at Hogwarts School of Witchcraft and Wizardry, Snape is hostile to Harry due to his resemblance to his father James Potter, who bullied Snape during their time together at Hogwarts. As the series progresses, Snape's character becomes more layered and enigmatic.
After her death, Dumbledore convinced him that the only way he could remain loyal to her and her memory was to keep her son safe. And D convinced Snape that the only way he could do that was to become part of Dumbledore's plan. So yes, Snape was loyal to D because he had no other way to be true to himself and to Lily.
Lily brought light and warmth into Snape's life from the moment they met. He was an isolated, lonely child whose magic would have only made him more of an outsider in his hometown of Cokeworth.
According to the books, he didn't. He was a lonely child who could speak to no one until he found another child he could speak with. The few times we see their interactions they interact as friends, and it's clear that Sev loved his friend. Not so clear that Lily, in spite of her promises, loved him in any way.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.
From the moment he first burst into the potions classroom and said “there will be no foolish wand-waving or silly incantations” Snape was cemented as an iconic character. These are the most famous and iconic lines by Snape, that people love to re-use in memes or just among friends.
Similarly to Harry, Snape's patronus represents a person. In the memories he gives Harry before his death, Snape shows Dumbledore his patronus, using the form to prove his love of Lily Potter, Harry's mother.
He doesn't trust Snape as Dumbledore does, but he believes that he can detect any disloyalty. Moreover, Voldemort regards Snape as highly intelligent and therefore ' as a true Slytherin ' a person whose top priority is to take care of himself. To his twisted mind, selfless equals stupid.
It probably had at least a little bit to do with her friendship with Harry Potter. Additionally, her brilliance made it harder to favor the Slytherins. No matter the cause, it's clear that Snape loathed that Hermione was so smart and so willing to answer any and all questions during class.
Narcissa's greatest moment, however, was when she chose to betray Voldemort in Harry Potter and the Deathly Hallows. Not knowing whether Draco was alive or dead, Narcissa chose to lie to the Dark Lord rather than risk losing her son.
Draco says she suffers from a “blood malediction,” which ultimately ends up killing her the summer before Scorpius's third year. While it isn't clear that Astoria's and Nagini's conditions are the same, Draco's description of her illness seems to match up with new information from Rowling's tweets.
Ultimately, his need to survive and protect his family would lead Lucius to betray Voldemort. With the Dark Lord defeated, he and his wife Narcissa turned in every Death Eater they could to avoid being imprisoned in Azkaban.
Knowing that Snape has been on the Dumbledore's side for all seven of the Harry Potter books reveals him as an extremely brave man and a truly skilled spy. Snape has had to face and deceive the terrifying Lord Voldemort constantly.
He did not even wish he had chosen differently — he believed he had made the only reasonable choice. He felt what he said, regret. Because he had to kill his most useful servant. His other Death Eaters either fled or were imprisoned when Voldemort was 'half-dead'.