tenyeardrunks

       

silver-tongues-blog

That is just a small example. If you remember, Snape became the dark lords right hand man and lied entirely for years just to protect potter because lilly, who considered him at most a friend, asked him to. Not all slytherins are evil, they just want what they care about.

Hell, salazar slytherin believed he was protecting the wizard world from muggles because he considered muggles a threat. And voldemort was doing it for the same reason as well as he blamed his father, a muggle, for his mothers death.