I had a random conversation with Lady Slytherin. She’s a self proclaimed Slytherin who was sorted into Gryffindor in Pottermore.
Apparently, Lady Slytherin didn’t accept that. She never accepts it. Then she tried a YouTube quiz “Which Hogwarts House Are You in?” and was sorted into Gryffindor. She said, “I’m not evil enough.” After that, I showed her a BuzzFeed quiz “These Five Questions Will Tell You What Percent Slytherin You Are“. And her result? She’s 100% Slytherin.
This is a problem that bothers us. Many quizzes about Hogwarts house still consider Slytherin as evil. Lady Slytherin and I see Slytherin as a house with people who have “unique” priority and do their best to keep that priority safe.
Let’s take a look. Harry, Order of the Phoenix, and Dumbledore Army’s priority is to defeat Voldemort and the Death Eaters so people can live in peace. For that reason, they practice their magic and make strategies to defeat the dark wizards.
However, Slytherins have various priorities. For the Malfoys, their family matters. All that they do is to keep Malfoy family and lineage safe. Lucius stated that he had been under Imperius curse during the first Wizarding War (the one before Harry was born) then he wasn’t prisoned in Azkaban. Thus, Malfoy family was still safe, rich, and powerful. After Voldemort was back, Lucius declared his loyalty again. He did it because he knew what Voldemort was capable of and he didn’t want to risk his family.
For Snape, Lily was important. All of his act as double agent was motivated by his feeling for Lily. His motivation might not so “pure” as the other members of Order of the Phoenix. He still hated Harry at some point because Harry was James Potter’s son. However, as Harry himself said, Snape was the bravest man he ever knew.
And finally, let me talk about our infamous Slytherin, Tom Riddle aka. Voldemort. What did Voldemort consider important? Power and immortality. For those things, he was willing to read old books and travel the world. For those things, he was willing to live through the pain of splitting soul. And also for those things, he was willing to act polite and courteous to people (remember Helena Ravenclaw and Hepzibah Smith?).
Now I’m not saying that Slytherins are right. I’m saying that there’s nothing wrong with being Slytherin as long as you understand what truly matters to you.