Thus, the answer is simple - Snape mistreated Neville as he was nearly the chosen one. Had Voldemort picked Neville instead of Harry, Lily's life would have been spared. Snape relieved his dark past through Neville Longbottom and therefore resorted to mistreating and insulting the almost-chosen one of Harry Potter.
Neville Professor Snape Neville fears Professor Snape who treats him rudely with sarcastic comments. Neville seems afraid of this harsh treatment that makes him feel inferior constantly.
If Voldemort had made the Chosen One Neville, then he would not have survived Voldemort's murder attempt on him as a child. Snape would not have asked for him to protect anyone as he did not care for the Longbottoms, this may have meant he never became a double agent too.
Initially, Voldemort twisted Harry into the position by first looking at his lineage. Tom Riddle and Harry Potter were both half-bloods, which meant Harry was more like him than the pureblooded Neville. From there, Voldemort focused specifically on the Potters, who had defied him to no end.
Popular theory is because Neville was also a potential for being the Chosen One. His rationale being that if Val-Mart had went after Neville instead, Lily would still be alive. It's quite similar reasoning to why he hates Harry.
Thus, the answer is simple - Snape mistreated Neville as he was nearly the chosen one. Had Voldemort picked Neville instead of Harry, Lily's life would have been spared. Snape relieved his dark past through Neville Longbottom and therefore resorted to mistreating and insulting the almost-chosen one of Harry Potter.
Why did Snape hate Hermione? I think Snape was probably initially impressed with Hermione, but later frustrated with her, for a few reasons. Hermione was very book-smart and could come up with answers quickly, but didn't seem to be very good at improvising or trying to improve on existing Magic.
What would have happened if Voldemort went after Neville?
If Voldemort had located and attacked the Longbottoms, it is likely he would offer to spare neither Frank nor Alice—he did that to Lily, because Snape had explicitly asked him to. Without a real sacrifice, Neville would be dead immediately afterwards.
Voldemort intended Draco to die in the attempt to kill Dumbledore so that Lucius would be punished for his failure to retrieve the prophecy from the Ministry of Magic.
How did Lily and James Potter defy Voldemort three times?
James and Lily defied Voldemort 3 times
"If you're counting, which I do, any time you arrested one of his henchmen, any time you escaped him, any time you thwarted him. That's what he's looking for," she said. "And both couples qualified because they were both fighting."
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
The Prophecy states that the one with the power to vanquish the Dark Lord would be born at the end of July to parents who had defied Voldemort three times. Both Harry and Neville Longbottom fit this description, but Voldemort chose to apply the Prophecy to Harry.
Notably, Voldemort appeared to be entirely unaware of this split, as he later created a seventh Horcrux in his quest to have six, and continued to target Harry Potter despite him now holding part of Voldemort's own soul.
To defend her students, McGonagall casts a series of spells Snape's way, but he manages to evade all of them before flying away. But what McGonagall doesn't know is that Snape is actually a double agent working for Dumbledore, so he has no intention of harming her. That being said, Snape holds back quite a bit.
The flames became a ring of fire that filled the corridor and flew like a lasso at Snape. Snape then turned the descending flames into a great black snake that McGonagall blasted to smoke and turned into a swarm of daggers, which she directed towards him.
He first demonstrates the Imperius Curse, which allows the curser to control the cursed. This is the curse that Voldemort used to put wizards under his control). He then shows the Cruciatus Curse, which causes terrible writing pain to the cursed, and which upsets Neville tremendously when he sees it done to the spider.
J.K. Rowling says Draco doesn't have a patronus because he never learned the spell but I think it's because he doesn't have any powerful happy memories to use. He has tons of happy memories... He had an amazing childhood. However, she also said Snape was the only Death Eater who could produce a Patronus.
In his memoir, Felton said that Fiennes improvised Voldemort awkwardly hugging Draco Malfoy. "It gave me goosebumps then, and the memory gives me goosebumps now," Felton wrote.
In Harry Potter and the Deathly Hallows Part 2, Neville is actually the person who destroys Voldemort's last Horcrux in Nagini, rendering him mortal, meaning that he and Harry truly delivered the final blows to Voldemort.
In the books it is made explicitly clear that Neville or Harry could be the chosen one as both were males born on the last couple of days of July in 1980, and both parents were a threat to Voldemort, and both parents were taken out by Voldemort/his supporters.
Voldemort would only keep one house: Slytherin and would destroy The Sorting Hat. He would kill all of Harry's friends except (probably since mentioned) the Weasleys since they are purebloods.
Umbridge earns far more hate than Snape. While Gryffindors have to deal with Snape's biased behavior during potions class, Umbridge creates rules that affect all school life. Her educational decrees are constantly banning one thing or another.
For example, Lily Evans told her former friend Severus Snape that if he was going to refer to other Muggle-borns as "Mudbloods", then he had to use the term for her as well, not minding it much when he did so. Hermione Granger declared that she was proud to be a "Mudblood" in 1998.
He simply didn't value the Gryffindor traits as much as he valued others. We really don't see much of an average day's activity at Hogwarts, so it is hard to say. Maybe Snape gets on just fine with quiet Gryffindors. We would need to see how Snape interacts with Ravenclaws and Hufflepuffs as well for comparison.
