Another weird thing is his appearance. Sometimes half-bloods (like Snape himself) got into the green-silver house. But if they didn’t inherit their magical parents surname or physical appearance, there's a high chance of bullying inside Slytherin. The internal unity is complete bullshit: snake lair cannot be either peaceful or friendly, if you don't prove that you deserve it. Purebloods pretend to be the noble and sublime, but in reality they are the true tumors of society, who will never stoop to a simple muggle fist fight, but will be glad to use magic or "word art" instead.